Bump mkdocs-material from 9.6.18 to 9.6.21#9

dependabot[bot] wants to merge 1 commit intomainlinuxserver/docker-documentation:mainfrom

dependabot/pip/mkdocs-material-9.6.21linuxserver/docker-documentation:dependabot/pip/mkdocs-material-9.6.21Copy head branch name to clipboard