Indent allowlist_for_publicAPI.json entries
Having the entire file on one line like this means it's not only less
human readabled, but also it's guarunteed to create merge conflict if
two PRs change it at around the same time.
Generated with the following code:
```
with open('allowlist_for_publicAPI.json', 'r') as f:
allow_list = json.load(f)
with open('allowlist_for_publicAPI.json', 'w') as f:
f.write(json.dumps(allow_list, indent=2))
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75792
Approved by: https://github.com/albanD
