Remove Python 3.4 support (#3147)

Closes #3123

stdlib/2and3/binascii.pyi

@@ -5,20 +5,15 @@
 import sys
 from typing import Union, Text
 
-
 if sys.version_info < (3,):
     # Python 2 accepts unicode ascii pretty much everywhere.
-    _Bytes = Union[bytes, Text]
-    _Ascii = Union[bytes, Text]
-elif sys.version_info < (3, 3):
-    # Python 3.2 and below only accepts bytes.
-    _Bytes = bytes
-    _Ascii = bytes
+    _Bytes = Text
+    _Ascii = Text
 else:
     # But since Python 3.3 ASCII-only unicode strings are accepted by the
     # a2b_* functions.
     _Bytes = bytes
-    _Ascii = Union[bytes, Text]
+    _Ascii = Union[bytes, str]
 
 def a2b_uu(string: _Ascii) -> bytes: ...
 if sys.version_info >= (3, 7):