Bump sphinx from 7.2.5 to 7.2.6 in /docs/readthedocs (#885)

Author: dependabot[bot]

docs/readthedocs/requirements.txt

@@ -1,6 +1,6 @@
 commonmark==0.9.1
 recommonmark==0.7.1
-Sphinx==7.2.5
+Sphinx==7.2.6
 sphinx-rtd-theme==1.3.0
 myst-parser==2.0.0
 markdown-it-py==3.0.0