Add a command to format python code

lib/python/qmk/cli/pyformat.py

@@ -0,0 +1,16 @@
+"""Format python code according to QMK's style.
+"""
+from milc import cli
+
+import subprocess
+
+
+@cli.entrypoint("Format python code according to QMK's style.")
+def main(cli):
+    """Format python code according to QMK's style.
+    """
+    try:
+        subprocess.run(['yapf', '-vv', '-ri', 'bin/qmk', 'lib/python'], check=True)
+        cli.log.info('Successfully formatted the python code in `bin/qmk` and `lib/python`.')
+    except subprocess.CalledProcessError:
+        cli.log.error('Error formatting python code!')