Remove Python 3.8 support (#11321)

Closes #10086
Authored by: bashonly

yt_dlp/compat/compat_utils.py

@@ -57,7 +57,7 @@ def passthrough_module(parent, child, allowed_attributes=(..., ), *, callback=la
         callback(attr)
         return ret
 
-    @functools.lru_cache(maxsize=None)
+    @functools.cache
     def from_child(attr):
         nonlocal child
         if attr not in allowed_attributes:

yt_dlp/compat/functools.py

@@ -5,8 +5,3 @@ from .compat_utils import passthrough_module
 
 passthrough_module(__name__, 'functools')
 del passthrough_module
-
-try:
-    _ = cache  # >= 3.9
-except NameError:
-    cache = lru_cache(maxsize=None)