Remove deprecation module

Going forward, we'll use type stubs / simple warnings for
deprecations.

Author: WyattBlue

av/__main__.py

@@ -1,7 +1,9 @@
+from __future__ import annotations
+
 import argparse
 
 
-def main():
+def main() -> None:
     parser = argparse.ArgumentParser()
     parser.add_argument("--codecs", action="store_true")
     parser.add_argument("--version", action="store_true")
@@ -13,7 +15,7 @@ def main():
 
         print(f"PyAV v{av.__version__}")
 
-        by_config = {}
+        by_config: dict = {}
         for libname, config in sorted(av._core.library_meta.items()):
             version = config["version"]
             if version[0] >= 0:

av/codec/context.pyx

@@ -11,7 +11,6 @@ from av.error cimport err_check
 from av.packet cimport Packet
 from av.utils cimport avrational_to_fraction, to_avrational
 
-from av.deprecation import AVDeprecationWarning
 from av.dictionary import Dictionary