Prepare for the 3.10 beta release

[pablogsal]

Once we publish the first beta release for Python 3.10 we need to make sure that miss-islington supports:

• The 3.10 backport label.
• The rename of master to main.

It would be ideal if we can synchronize so this is ready for the release :)

CC: @brettcannon @Mariatta

[Mariatta]

There shouldn't be any issue with supporting the 3.10 label. We can update the test case to be sure, perhaps by parametrizing it.

miss-islington/tests/test_backport_pr.py

Line 123 in ac121b7

{"name": "needs backport to 3.7"},

Re branch rename, the easiest is by creating the cherry-picker.toml file that specifies the default_branch config value. I will look into preparing the PR for it, and wait for it to be merged until after the 3.10 release. (documentation)

There is also an open ticket for supporting the main branch by default. python/cherry-picker#21

[Mariatta]

Added test that we can backport to the 3.10 branch correctly: #453 This should be safe to be merged now.

Added the config for the main branch. #452 This should wait until we have the main branch.