release/0.21.2

## What's Changed
- Fixes a 0.21.1 regression where a pull request cache left by an older version could break the workspace after upgrading
- Fixes an issue where updating a branch from upstream could fail
- Bitbucket: Fixes an issue where build status checks could fail to load in some cases
- Fixes an issue where a "part 1 of 1 in a stack" footer could be added to pull requests that aren't part of a stack

**Full Changelog**: https://github.com/gitbutlerapp/gitbutler/compare/release/0.21.1...release/0.21.2

## Downloads
Download bins from https://gitbutler.com/