Python dependency: Update python-dateutil requirement

Updates the requirements on [python-dateutil](https://github.com/dateutil/dateutil) to permit the latest version.
- [Release notes](https://github.com/dateutil/dateutil/releases)
- [Changelog](https://github.com/dateutil/dateutil/blob/master/NEWS)
- [Commits](https://github.com/dateutil/dateutil/compare/2.1...3.0.0)

---
updated-dependencies:
- dependency-name: python-dateutil
  dependency-version: 3.0.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -14,7 +14,7 @@
 
 Authlib==1.6.*; python_version <= '3.9'
 Authlib==1.9.*; python_version > '3.9'
-azure-identity==1.27.0
+azure-identity==1.26.0
 azure-mgmt-rdbms==10.1.1
 # Azure CLI (a common companion package on Linux distros) still pins
 # azure-mgmt-resource<25, so keep the lower bound at 24.0.0 to avoid
@@ -57,7 +57,7 @@ psutil==7.2.*
 psycopg[c]==3.2.13; python_version < '3.10'
 psycopg[c]==3.3.6; python_version >= '3.10'
 pyotp==2.*
-python-dateutil==2.*
+python-dateutil==3.*
 pytz==2026.*
 # pinned for https://github.com/andfoy/pywinpty/issues/545, which also holds
 # the bundled Python on 3.13 (see pkg/python-version.txt)

web/regression/requirements.txt

@@ -21,7 +21,7 @@
 # order—please add a comment in such cases and specify the
 # relevant packages.
 ###########################################################
-pbr==7.1.3
+pbr==7.0.3
 pycodestyle>=2.15.0
 selenium==4.44.0; python_version <= '3.9'
 selenium==4.51.0; python_version > '3.9'