Fix mypy violations (for mypy-0.711)

setup.py

@@ -47,7 +47,7 @@ extras_require = {
         'html5lib',
         'flake8>=3.5.0',
         'flake8-import-order',
-        'mypy>=0.710',
+        'mypy>=0.711',
         'docutils-stubs',
     ],
 }

sphinx/util/inspect.py

@@ -129,7 +129,7 @@ def isenumattribute(x):
 def ispartial(obj):
     # type: (Any) -> bool
     """Check if the object is partial."""
-    return isinstance(obj, (partial, partialmethod))  # type: ignore
+    return isinstance(obj, (partial, partialmethod))
 
 
 def isclassmethod(obj):