bump to python 3.7 (#11408)

lib/python/qmk/cli/__init__.py

@@ -27,6 +27,24 @@ from . import new
 from . import pyformat
 from . import pytest
 
-if sys.version_info[0] != 3 or sys.version_info[1] < 6:
-    cli.log.error('Your Python is too old! Please upgrade to Python 3.6 or later.')
+# Supported version information
+#
+# Based on the OSes we support these are the minimum python version available by default.
+# Last update: 2021 Jan 02
+#
+# Arch: 3.9
+# Debian: 3.7
+# Fedora 31: 3.7
+# Fedora 32: 3.8
+# Fedora 33: 3.9
+# FreeBSD: 3.7
+# Gentoo: 3.7
+# macOS: 3.9 (from homebrew)
+# msys2: 3.8
+# Slackware: 3.7
+# solus: 3.7
+# void: 3.9
+
+if sys.version_info[0] != 3 or sys.version_info[1] < 7:
+    cli.log.error('Your Python is too old! Please upgrade to Python 3.7 or later.')
     exit(127)