Videos always play on 1080p, even after selecting 720p

[SirGorak]

Behavior of the program
Video always plays on the highest resolution, 1080p

Expected behavior
It should play on 720p, like I selected in the settings

To Reproduce
Please add all steps to reproduce the behavior:

1. Go to settings
2. Click on 720p
3. Play a video
4. It's on 1080p

Environment Information (please complete the following information):

• OS: Ubuntu
• OS Version: KDE Neon 5.21
• FreeTube version: 0.11.3 beta
• Installation Method (If applicable): Flathub
• Primary API Used: Local API

[GilgusMaximus]

As mentioned on other issues, this is related to what VideoJS and the video streaming plugin do under the hood. It is, in terms of reason to occur, a duplicate of #595