No, you must simply modify the branch on your fork and the PR updates automatically. In this case, I suggest you rewrite the commit by changing the file again then using:

```shell
git add .
git commit --amend
( save and close editor )
git push origin master --force
```

The `--force` will be required because you're rewriting a commit that was already pushed to your fork on GitHub. This is only advised for code that hasn't been merged to a trunk yet.