Changelog and contributors tools can fail to find PRs

[alice-i-cecile]

IMO: all of the missed PRs look like they got excluded because they were originally opened before the "from" date for the release

• @ChristopherBiscardi

Discovered in #1516 / #1517.

[ChristopherBiscardi]

get_issues_and_prs gets all PRs since the origin date, which is going to be roughly 0.<last_major>.1's date. That set of PRs is what is is checked so any PR opened before that will not be included because the issues endpoint can not be sorted by "closed date". I believe the default sorting for the issues endpoint is "id, descending".

The older PRs may have to be fetched by id.

[alice-i-cecile]

Cutting from the milestone. This is still important to do, but I did them manually this time around.

[alice-i-cecile]

In #1850, I'm no longer filtering the PRs by date. This helps: we found another half-dozen PRs! It doesn't fully resolve the mismatch though :( Dozens of PRs were still not found.

[alice-i-cecile]

We're using a title match to correlate commits against PRs. In some cases, like bevyengine/bevy#15320, that's definitely because we renamed the PR after it was merged, so the commit name and the PR title don't match. I have no good ideas for how to resolve that.

But there's dozens of other PRs, which seemingly don't share that problem. See bevyengine/bevy#14122 for example. The PR exists, it hasn't been renamed. Perhaps there's another date check that I'm missing?