Merge pull request #266 from beeware/pyupgrade-3.7

Update pyupgrade to set py3.7 minimum

Author: mhsmith

.pre-commit-config.yaml

@@ -17,7 +17,7 @@ repos:
     rev: v3.3.1
     hooks:
       - id: pyupgrade
-        args: [--py36-plus]
+        args: [--py37-plus]
   - repo: https://github.com/psf/black
     rev: 23.1.0
     hooks:

changes/266.misc.rst

@@ -0,0 +1 @@
+A backwards compatibility shim for Python 3.6 was removed.

docs/background/releases.rst

@@ -9,7 +9,7 @@ Release History
 Features
 --------
 
-* Support for Python 3.6 was dropped. (#371)
+* Support for Python 3.6 was dropped. (#255)
 
 Misc
 ----

src/rubicon/objc/eventloop.py

@@ -1,6 +1,6 @@
 """PEP 3156 event loop based on CoreFoundation."""
 
-import sys
+import contextvars
 import threading
 from asyncio import (
     DefaultEventLoopPolicy,
@@ -324,21 +324,13 @@ def cancel(self):
 
 
 def context_callback(context, callback):
-    # Python 3.7 introduced the idea of context variables.
-    # asyncio.call_{at,later,soon} need to run any callbacks
-    # *inside* the context provided.
-    if sys.version_info >= (3, 7):
-        import contextvars
+    if context is None:
+        context = contextvars.copy_context()
 
-        if context is None:
-            context = contextvars.copy_context()
+    def _callback(*args):
+        context.run(callback, *args)
 
-        def _callback(*args):
-            context.run(callback, *args)
-
-        return _callback
-    else:
-        return callback
+    return _callback
 
 
 class CFEventLoop(unix_events.SelectorEventLoop):