Use squash-merge when merging PRs

[faridyagubbayli]

Most of the PRs include work in progress commits. I think we should avoid adding those commits to the main branch and use squash-merge. This way we will have a single commit per PR in the main branch. It should also help if we need to revert a particular PR in the main. What do people think?

[waltsims]

I think this makes sense :)

[waltsims]

The argument against this is that it deletes history needlessly. It also makes catch up merges potentially harder to understand.