[BUGFIX] Add video/x-m4v to supported mime types of VideoTagRenderer

Some videos might use the mime type video-x-m4v. To render those, the
mime type must be added to the list of supported mime types of the
renderer.

Resolves: #81817
Releases: master, 8.7
Change-Id: I0420009fe5ca55698d2aeb4727dbf6a7df7c981e
Reviewed-on: https://review.typo3.org/53430


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Tested-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Frans Saris <franssaris@gmail.com>
Reviewed-by: Daniel Maier <dani-maier@gmx.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>