Add flake8 to our test suite and fix all errors (#7379)

* Add flake8 to our test suite and fix all errors

* Add some documentation

bin/qmk

@@ -41,7 +41,7 @@ else:
     os.environ['QMK_VERSION'] = 'nogit-' + strftime('%Y-%m-%d-%H:%M:%S') + '-dirty'
 
 # Setup the CLI
-import milc
+import milc  # noqa
 
 milc.EMOJI_LOGLEVELS['INFO'] = '{fg_blue}Ψ{style_reset_all}'
 
@@ -61,7 +61,7 @@ def main():
     os.chdir(qmk_dir)
 
     # Import the subcommands
-    import qmk.cli
+    import qmk.cli  # noqa
 
     # Execute
     return_code = milc.cli()