Merge branch 'hotfix/3.0.4'
Fix the `.gitattributes` file
Correctly load the language files (see #5384)
Update the forum link in the referer error message (see #5389)
Remove the pixel unit from the video width and height attributes (see #5383)
Merge branch 'hotfix/3.0.5' into develop

Conflicts:
	system/docs/CHANGELOG.md
	system/modules/core/library/Contao/System.php
	system/modules/core/templates/be_referer.html5