Remove some 3.6 legacy (#13349)

Author: sobolevn

mypy/typeops.py

@@ -6,7 +6,6 @@
 """
 
 import itertools
-import sys
 from typing import (
     Any,
     Dict,
@@ -857,14 +856,6 @@ class Status(Enum):
                 if name in ENUM_REMOVED_PROPS:
                     continue
                 new_items.append(LiteralType(name, typ))
-            # SymbolTables are really just dicts, and dicts are guaranteed to preserve
-            # insertion order only starting with Python 3.7. So, we sort these for older
-            # versions of Python to help make tests deterministic.
-            #
-            # We could probably skip the sort for Python 3.6 since people probably run mypy
-            # only using CPython, but we might as well for the sake of full correctness.
-            if sys.version_info < (3, 7):
-                new_items.sort(key=lambda lit: lit.value)
             return make_simplified_union(new_items, contract_literals=False)
         elif typ.type.fullname == "builtins.bool":
             return make_simplified_union(

mypy/util.py

@@ -426,10 +426,10 @@ def get_unique_redefinition_name(name: str, existing: Container[str]) -> str:
 def check_python_version(program: str) -> None:
     """Report issues with the Python used to run mypy, dmypy, or stubgen"""
     # Check for known bad Python versions.
-    if sys.version_info[:2] < (3, 6):
+    if sys.version_info[:2] < (3, 7):
         sys.exit(
-            "Running {name} with Python 3.5 or lower is not supported; "
-            "please upgrade to 3.6 or newer".format(name=program)
+            "Running {name} with Python 3.6 or lower is not supported; "
+            "please upgrade to 3.7 or newer".format(name=program)
         )