Feature request: Restrict deletion of previous comments to current user

`GITHUB_DELETE_COMMENT_REGEX` can be used to delete previous comments before posting the new one. The current implementation will delete matching comments regardless of who they were posted by. This can easily lead to false positives where someone happens to post comment that matches your regex (due to loose regex, or quoting, etc).

I do not see a use case to delete comments by others, and recommend restricting it to the user that the tool is running as.