Use new auth (#214)

# Exercise Review

## Exercise Discussion

Link the exercise discussion issue

## Checklist

- [ ] If you require a new remote repository on the `Git-Mastery`
organization, have you [created a
request](https://github.com/git-mastery/exercises/issues/new?template=request_exercise_repository.md)
for it?
- [ ] Have you written unit tests using
[`repo-smith`](https://github.com/git-mastery/repo-smith) to validate
the exercise grading scheme?
- [ ] Have you tested your changes using the instructions posted?
- [ ] Have you verified that this exercise does not already exist or is
not currently in review?
- [ ] Did you introduce a new grading mechanism that should belong to
[`git-autograder`](https://github.com/git-mastery/git-autograder)?
- [ ] Did you introduce a new dependency that should belong to
[`app`](https://github.com/git-mastery/app)?

Author: woojiahao

scripts/post-contribution-message.py

@@ -1,6 +1,6 @@
 import os
 
-from github import Github
+from github import Github, Auth
 
 GITHUB_TOKEN = os.environ.get("GITHUB_TOKEN")
 PR_NUMBER = os.environ.get("PR_NUMBER")
@@ -17,7 +17,10 @@
 assert PR_NUMBER is not None
 PR_NUMBER_INT = int(PR_NUMBER)
 
-gh = Github(GITHUB_TOKEN)
+assert GITHUB_TOKEN is not None
+
+auth = Auth.Token(GITHUB_TOKEN)
+gh = Github(auth=auth)
 repo = gh.get_repo("git-mastery/exercises")
 pr = repo.get_pull(PR_NUMBER_INT)