add .m4v video format type

[tzarebczan]

It's a container type very similar to mp4. Someone recently added one in the community top bids section.

PR Checklist

Please check all that apply to this PR using "x":

• I have checked that this PR is not a duplicate of an existing PR (open, closed or merged)
• I have checked that this PR does not introduce a breaking change
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PR Type

What kind of change does this PR introduce?

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• Bugfix
• Feature
• Breaking changes (bugfix or feature that introduces breaking changes)
• Code style update (formatting)
• Refactoring (no functional changes)
• Documentation changes
• Other - Please describe:

Fixes

Issue Number: N/A

What is the current behavior?

What is the new behavior?

Other information

[codecov]

Codecov Report

Merging #1764 into master will increase coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1764      +/-   ##
==========================================
+ Coverage   63.84%   63.98%   +0.13%     
==========================================
  Files         150      150              
  Lines       13647    13766     +119     
==========================================
+ Hits         8713     8808      +95     
- Misses       4934     4958      +24

Impacted Files	Coverage Δ
lbrynet/extras/daemon/mime_types.py	100% <ø> (ø)	⬆️
lbrynet/extras/daemon/DaemonConsole.py	37.37% <0%> (-0.06%)	⬇️
lbrynet/schema/uri.py	96.72% <0%> (+1.06%)	⬆️
lbrynet/extras/daemon/analytics.py	64.15% <0%> (+6.05%)	⬆️
lbrynet/extras/looping_call_manager.py	75% <0%> (+12.5%)	⬆️

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