[3.10] [3.11] Docs: pin python-docs-theme to 2025.2 (pythonGH-129576)

* [3.11] Pin python-docs-theme

* Use today's release

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

---------
(cherry picked from commit 77ca2f6)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: AA-Turner

Doc/requirements.txt

@@ -15,6 +15,6 @@ blurb
 
 # The theme used by the documentation is stored separately, so we need
 # to install that as well.
-python-docs-theme>=2022.1
+python-docs-theme==2025.2
 
 -c constraints.txt