chore(deps): update dependency mkdocs-material to v9.6.15 (#1965)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

docs/requirements.txt

@@ -1,4 +1,4 @@
 mkdocs-git-revision-date-localized-plugin==1.4.7
-mkdocs-material==9.6.14
+mkdocs-material==9.6.15
 mkdocs-minify-plugin==0.8.0
 mkdocs-redirects==1.2.2