fix recently updated PR checker

[AyodeAwe]

Updates the recently_updated plugin to correctly filter out forward merger PRs.

[ajschmidt8]

these changes look good to me.

are there any other areas where the isGPUTesterPR function should be replaced? is this function needed anymore? are all of the automated PRs now opened by the rapids-bot?

[AyodeAwe]

these changes look good to me.

are there any other areas where the isGPUTesterPR function should be replaced? is this function needed anymore? are all of the automated PRs now opened by the rapids-bot?

I think there are a few places we need to update, but these don't have to go in this PR. I am making a note of these and I will create an issue today.

[AyodeAwe]

Ray and I are discussing switching the release PRs back to being authored by GPUTester, which would mean we need to continue accounting for it in the branch_checker plugin and re-introduce it into the recently_updated plugin.

But this might require a significant refactoring of the test fixtures in the code base. So I think we can separately get this PR merged as a fix for the issue reported in ops#3624