Update automerger to merge from 6.3 to main

[itingliu]

Now that we have branched for 6.3, update automerger to merge from 6.3 to main.

While we are not currently running automerger to merge into the release branch, update the version in automerge_to_release.yml as well for consistency.

As part of this, we will also disable merge -> future workflow from github action.

[itingliu]

@swift-ci please test

[itingliu]

@swift-ci please test

[jmschonfeld]

I think we'll want to target this at the main branch even though it's related to the release branch (since that's where GitHub will pick up the configuration for auto mergers that run on a schedule)

[itingliu]

I think we'll want to target this at the main branch even though it's related to the release branch (since that's where GitHub will pick up the configuration for auto mergers that run on a schedule)

Sure. I was just thinking that 6.3 will get forwarded to main, so it'll end up there anyways... but I updated it!

[itingliu]

@swift-ci please test