Remove response.data.status check

It's perfectly valid for a head to be "behind" a base when comparing commits for pull request events. For example, PRing a feature branch of `main` while other commits have landed on `main` after the feature branch was started but before the PR was created, or a PR to merge a "development" branch onto a slower moving "release" branch that has some hotfixes on it.

src/main.ts

@@ -76,14 +76,6 @@ async function run(): Promise<void> {
       )
     }
 
-    // Ensure that the head commit is ahead of the base commit.
-    if (response.data.status !== 'ahead') {
-      core.setFailed(
-        `The head commit for this ${context.eventName} event is not ahead of the base commit. ` +
-          "Please submit an issue on this action's GitHub repo."
-      )
-    }
-
     const regex = new RegExp(`/${filter}\\b`, 'g')
     // Get the changed files from the response payload.
     const files = response.data.files.filter(file => file.filename.match(regex))