Correct PeertubePlaylistExtractorTest unit tests

[gliptak]

• I carefully read the contribution guidelines and agree to them.
• I have tested the API against NewPipe.
• I agree to create a pull request for NewPipe as soon as possible to make it compatible with the changed API.

https://github.com/TeamNewPipe/NewPipeExtractor/runs/6944735436?check_suite_focus=true

PeertubePlaylistExtractorTest$Shocking > testGetSubChannelAvatarUrl() FAILED
    org.opentest4j.AssertionFailedError: expected: <https://framatube.org/lazy-static/avatars/f1dcd0e8-e651-42ed-ae81-bb3bd4aff2bc.png> but was: <https://framatube.org/lazy-static/avatars/e801ccce-8694-4309-b0ab-e6f0e552ef77.png>
        at org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
        at org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62)
        at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:182)
        at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:177)
        at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1141)
        at org.schabi.newpipe.extractor.services.peertube.PeertubePlaylistExtractorTest$Shocking.testGetSubChannelAvatarUrl(PeertubePlaylistExtractorTest.java:71)
PeertubePlaylistExtractorTest$Shocking > testGetUploaderAvatarUrl() FAILED
    org.opentest4j.AssertionFailedError: expected: <https://framatube.org/lazy-static/avatars/cd0f781d-0287-4be2-94f1-24cd732337b2.jpg> but was: <https://framatube.org/lazy-static/avatars/c6801ff9-cb49-42e6-b2db-3db623248115.jpg>
        at org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
        at org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62)
        at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:182)
        at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:177)
        at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1141)
        at org.schabi.newpipe.extractor.services.peertube.PeertubePlaylistExtractorTest$Shocking.testGetUploaderAvatarUrl(PeertubePlaylistExtractorTest.java:46)

[litetex]

Ty for the PR

LGTM :)