[3.12] Docs: Upgrade to Sphinx 7.3 (GH-118397) (#118400)

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: miss-islington

.github/workflows/reusable-docs.yml

@@ -55,7 +55,7 @@ jobs:
       run: |
         set -Eeuo pipefail
         # Build docs with the '-n' (nit-picky) option; write warnings to file
-        make -C Doc/ PYTHON=../python SPHINXOPTS="-q -n -W --keep-going -w sphinx-warnings.txt" html
+        make -C Doc/ PYTHON=../python SPHINXOPTS="--quiet --nitpicky --fail-on-warning --keep-going --warning-file sphinx-warnings.txt" html
     - name: 'Check warnings'
       if: github.event_name == 'pull_request'
       run: |

Doc/requirements.txt

@@ -6,7 +6,7 @@
 # Sphinx version is pinned so that new versions that introduce new warnings
 # won't suddenly cause build failures. Updating the version is fine as long
 # as no warnings are raised by doing so.
-sphinx~=7.2.0
+sphinx~=7.3.0
 
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