Remove trailing comma from hooks.json and fix SyntaxWarning in Python 3.12

[regunakyle]

This pull request does 2 things:

1. Update the json_minify function in hooks to match the upstream version. One benefit is that it fixes SyntaxWarning that shows up in Python 3.12. I have tested it using my own hooks.json and can confirm that both version produce the same output
2. Remove the trailing comma in hooks.json. The previous pull request left the comma there, and the json_minify function can't deal with it, so it crashes the hook