chore(deps): bump pymdown-extensions to 11.0.1 and mkdocs-material to 9.7.7

pymdown-extensions 11.0 cannot be installed alongside mkdocs-material
9.5.49, which pins pymdown-extensions~=10.2 (i.e. <11), so Dependabot's
standalone bump fails the strict docs build with ResolutionImpossible.

mkdocs-material 9.7.7 relaxes the constraint to pymdown-extensions>=10.2,
so bump both together. Verified with `mkdocs build --strict`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: stubbi

docs-site/requirements.txt

@@ -1,3 +1,3 @@
 mkdocs==1.6.1
-mkdocs-material==9.5.49
-pymdown-extensions==10.21.3
+mkdocs-material==9.7.7
+pymdown-extensions==11.0.1