Retarget to Sphinx 9.0 (#14093)

doc/usage/configuration.rst

@@ -1157,9 +1157,9 @@ Options for source files
    The recommended encoding is ``'utf-8-sig'``.
 
    .. versionadded:: 0.5
-   .. deprecated:: 8.3
+   .. deprecated:: 9.0
       Support for source encodings other than UTF-8 is deprecated.
-      Sphinx 10 will only support UTF-8 files.
+      Sphinx 11 will only support UTF-8 files.
 
 .. confval:: source_suffix
    :type: :code-py:`dict[str, str] | Sequence[str] | str`
@@ -3671,7 +3671,7 @@ and which failures and redirects it ignores.
 
    .. versionadded:: 4.1
 
-   .. versionchanged:: 8.3
+   .. versionchanged:: 9.0
       Setting :confval:`!linkcheck_allowed_redirects` to an empty dictionary
       may now be used to warn on all redirects encountered
       by the *linkcheck* builder.
@@ -3847,7 +3847,7 @@ and the number of workers to use.
    .. note:: URI fragments (HTML anchors) are not affected by this option.
              They are always checked with case-sensitive comparisons.
 
-   .. versionadded:: 8.3
+   .. versionadded:: 9.0
 
 .. confval:: linkcheck_rate_limit_timeout
    :type: :code-py:`int`

doc/usage/extensions/autodoc.rst

@@ -971,7 +971,7 @@ Automatically document type aliases
 
 .. rst:directive:: autotype
 
-   .. versionadded:: 8.3
+   .. versionadded:: 9.0
 
    Document a :pep:`695` type alias (the :keyword:`type` statement).
    By default, the directive only inserts the docstring of the alias itself:
@@ -1008,7 +1008,7 @@ There are also config values that you can set:
    :default: :code-py:`False`
 
    If true, autodoc will use the legacy class-based implementation.
-   This is the behaviour prior to Sphinx 8.3.
+   This is the behaviour prior to Sphinx 9.0.
    It is based on the ``Documenter`` class hierarchy.
 
    This setting is provided for backwards compatibility if your documentation

doc/usage/extensions/doctest.rst

@@ -459,4 +459,4 @@ The doctest extension uses the following configuration values:
 
    Exit when the first failure is encountered.
 
-   .. versionadded:: 8.3
+   .. versionadded:: 9.0

doc/usage/extensions/math.rst

@@ -346,7 +346,7 @@ Sphinx but is set to automatically include it from a third-party site.
 
    __ https://docs.mathjax.org/en/latest/web/configuration.html#configuration
 
-   .. versionadded:: 8.3
+   .. versionadded:: 9.0
 
 :mod:`sphinxcontrib.jsmath` -- Render math via JavaScript
 ---------------------------------------------------------

doc/usage/restructuredtext/directives.rst

@@ -552,7 +552,7 @@ Describing changes between versions
       There must be no blank line between the directive head and the explanation;
       this is to make these blocks visually continuous in the markup.
 
-   .. version-changed:: 8.3
+   .. version-changed:: 9.0
       The :rst:dir:`versionadded` directive was renamed to :rst:dir:`version-added`.
       The previous name is retained as an alias.
 
@@ -570,7 +570,7 @@ Describing changes between versions
    Similar to :rst:dir:`version-added`, but describes when and what changed in
    the named feature in some way (new parameters, changed side effects, etc.).
 
-   .. version-changed:: 8.3
+   .. version-changed:: 9.0
       The :rst:dir:`versionchanged` directive was renamed to :rst:dir:`version-changed`.
       The previous name is retained as an alias.
 
@@ -590,7 +590,7 @@ Describing changes between versions
    A *brief* explanation can also be given,
    for example to tell the reader what to use instead.
 
-   .. version-changed:: 8.3
+   .. version-changed:: 9.0
       The :rst:dir:`deprecated` directive was renamed to :rst:dir:`version-deprecated`.
       The previous name is retained as an alias
 
@@ -611,7 +611,7 @@ Describing changes between versions
 
    .. version-added:: 7.3
 
-   .. version-changed:: 8.3
+   .. version-changed:: 9.0
       The :rst:dir:`versionremoved` directive was renamed to :rst:dir:`version-removed`.
       The previous name is retained as an alias.
 
@@ -1492,7 +1492,7 @@ Check the :confval:`latex_table_style`.
    complex contents such as multiple paragraphs, blockquotes, lists, literal
    blocks, will render correctly to LaTeX output.
 
-.. versionchanged:: 8.3.0
+.. versionchanged:: 9.0
    The partial support of the LaTeX builder for nesting a table in another
    has been extended.
    Formerly Sphinx would raise an error if ``longtable`` class was specified
@@ -1579,12 +1579,12 @@ Check the :confval:`latex_table_style`.
    preamble, as in fact Sphinx uses ``T`` and sets it by default to be an
    alias of ``J``.
 
-.. versionchanged:: 8.3.0
+.. versionchanged:: 9.0
 
    Formerly, Sphinx did not use ``tabulary`` if the table had at least one
    cell containing "problematic" elements such as lists, object descriptions,
    blockquotes (etc...) because such contents are not out-of-the-box
-   compatible with ``tabulary``.  At ``8.3.0`` a technique, which was already
+   compatible with ``tabulary``.  At ``9.0`` a technique, which was already
    in use for merged cells, was extended to such cases, and the sole
    "problematic" contents are code-blocks and nested tables.  So tables
    containing (only) cells with multiple paragraphs, bullet or enumerated