[ie/Monstercat] Add extractor (#8133)

Closes #8067
Authored by: garret1317

yt_dlp/extractor/_extractors.py

@@ -1126,6 +1126,7 @@ from .mofosex import (
     MofosexEmbedIE,
 )
 from .mojvideo import MojvideoIE
+from .monstercat import MonstercatIE
 from .morningstar import MorningstarIE
 from .motherless import (
     MotherlessIE,