Add Bot for Backporting

[ianhi]

Problem

There are a few PRs that should have been backported to 1.x that were not. Such as: #1390

This is an easy mistake to make, and the extra friction of cherrypicking and making a new PR does not help.

Proposed Solution

Use a bot to manage the backports. I believe other projects in the ecosystem use: https://github.com/scientific-python/MeeseeksDev

For example: matplotlib/matplotlib#30790

Additional context

matplotlib seems to have it be automatically backported based on adding a merged PR to a github milestone.