`qmk format-json`: Force Unix line endings and ensure LF at EOF (#22901)

lib/python/qmk/cli/format/json.py

@@ -92,8 +92,8 @@ def format_json(cli):
     output = json.dumps(json_data, cls=json_encoder, sort_keys=True)
 
     if cli.args.inplace:
-        with open(cli.args.json_file, 'w+', encoding='utf-8') as outfile:
-            outfile.write(output)
+        with open(cli.args.json_file, 'w+', encoding='utf-8', newline='\n') as outfile:
+            outfile.write(output + '\n')
 
     # Display the results if print was set
     # We don't operate in-place by default, so also display to stdout