[cleanup] Remove obsolete Python compatibility code (#17357)

Authored by: doe1080

yt_dlp/networking/_helper.py

@@ -108,9 +108,7 @@ def make_ssl_context(
     context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
     context.check_hostname = verify
     context.verify_mode = ssl.CERT_REQUIRED if verify else ssl.CERT_NONE
-    # OpenSSL 1.1.1+ Python 3.8+ keylog file
-    if hasattr(context, 'keylog_filename'):
-        context.keylog_filename = os.environ.get('SSLKEYLOGFILE') or None
+    context.keylog_filename = os.environ.get('SSLKEYLOGFILE') or None
 
     # Some servers may reject requests if ALPN extension is not sent. See:
     # https://github.com/python/cpython/issues/85140

yt_dlp/networking/_requests.py

@@ -123,7 +123,7 @@ class RequestsResponseAdapter(Response):
         # Work around issue with `.read(amt)` then `.read()`
         # See: https://github.com/urllib3/urllib3/issues/3636
         if amt is None:
-            # compat: py3.9: Python 3.9 preallocates the whole read buffer, read in chunks
+            # Read in chunks to avoid preallocating a large buffer
             read_chunk = functools.partial(self.fp.read, 1 << 20, decode_content=True)
             return b''.join(iter(read_chunk, b''))
         # Interact with urllib3 response directly.

yt_dlp/networking/_urllib.py

@@ -296,13 +296,9 @@ class UrllibResponseAdapter(Response):
     """
 
     def __init__(self, res: http.client.HTTPResponse | urllib.response.addinfourl):
-        # addinfourl: In Python 3.9+, .status was introduced and .getcode() was deprecated [1]
-        # HTTPResponse: .getcode() was deprecated, .status always existed [2]
-        # 1. https://docs.python.org/3/library/urllib.request.html#urllib.response.addinfourl.getcode
-        # 2. https://docs.python.org/3.10/library/http.client.html#http.client.HTTPResponse.status
         super().__init__(
             fp=res, headers=res.headers, url=res.url,
-            status=getattr(res, 'status', None) or res.getcode(), reason=getattr(res, 'reason', None))
+            status=res.status, reason=getattr(res, 'reason', None))
 
     def read(self, amt=None):
         if self.closed: