chore(deps-dev): Update mkdocs requirement from ~=1.3.0 to ~=1.3.1 in /gh-pages (#3674)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

gh-pages/requirements-dev.txt

@@ -1,4 +1,4 @@
-mkdocs~=1.3.0
+mkdocs~=1.3.1
 mkdocs-awesome-pages-plugin~=2.7.0
 mkdocs-material~=8.3.9
 mkdocs-git-revision-date-plugin~=0.3.2