Fix CSS issues with main page.

2109.7 Release - Fixes testing and minor UI bugs. Removes PHP7.4 only dependencies.

Fix logo rendering in docs.

Fix logo colour.

Fix the logo color.

Dark mode for books list. Fix search bug.

Hotfix for broken 'Read' buttons.

Bugfix - caches weren't getting cleared/updated on publish.

Upgrade templates for mkdocs-material version 5.1.1

Bugfix for ExceptionSubscriber - now loads RedirectResponse class correctly.

(Version bump, 1.1.2 didn't include the commit!)

Bugfix for ExceptionSubscriber - now loads RedirectResponse class correctly.

Minor CSS fix for MkDocs generated page footers.

Adds two new commands for managing the cached git repositories.

  * `./bin/console repo:clear book/lang` - Removes the cached repository information from the filesystem.
  * `./bin/console repo:pull book/lang` - Performs a git pull against the cached repository to pull updated information from upstream.

Also adjusts some styling in-app.