update_post action produces an incorrect PR title

[bstansberry]

The update_post action works great in general, except it generates a PR with an incorrect title. For example:

https://github.com/wildfly/wildfly.org/pull/535/commits

I'm going to edit the title of that PR before merging so the merge commit in the log has a good message, but right now it says

'Update date of PR: embrace polite language '

The 'embrace polite language' bit is not relevant to the PR.

The commit message on the action's commit 'Update 2024-02-02-resteasy-glow.md blog date' is fine and would make a reasonable PR title.