Remove 3.7 workarounds

telethon/_network/connection/connection.py

@@ -263,7 +263,6 @@ class Connection(abc.ABC):
 
         if self._writer:
             self._writer.close()
-            if sys.version_info >= (3, 7):
             try:
                 await self._writer.wait_closed()
             except Exception as e:

telethon/errors/__init__.py

@@ -1,5 +1,3 @@
-import sys
-
 from ._custom import (
     ReadCancelledError,
     TypeNotFoundError,
@@ -25,24 +23,6 @@ from ._rpcbase import (
     _mk_error_type
 )
 
-if sys.version_info < (3, 7):
-    # https://stackoverflow.com/a/7668273/
-    class _TelethonErrors:
-        def __init__(self, _mk_error_type, everything):
-            self._mk_error_type = _mk_error_type
-            self.__dict__.update({
-                k: v
-                for k, v in everything.items()
-                if isinstance(v, type) and issubclass(v, Exception)
-            })
-
-        def __getattr__(self, name):
-            return self._mk_error_type(name=name)
-
-    sys.modules[__name__] = _TelethonErrors(_mk_error_type, globals())
-else:
 # https://www.python.org/dev/peps/pep-0562/
 def __getattr__(name):
     return _mk_error_type(name=name)
-
-del sys