Refs -- Restored PY36 and PY37 version constants.
Partially reverts
PY36 should be removed when Django 2.2 is EOL.
PY37 should be removed when Django 3.2 is EOL.
Thanks to Tim Graham for the report.
@@ -9,6 +9,8 @@ from distutils.version import LooseVersion
# or later". So that third-party apps can use these values, each constant
# should remain as long as the oldest supported Django version supports that
# Python version.
+PY36 = sys.version_info >= (3, 6)
+PY37 = sys.version_info >= (3, 7)
PY38 = sys.version_info >= (3, 8)
PY39 = sys.version_info >= (3, 9)
