github/workflows: Bump actions/setup-python from 1 to 4.

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 1 to 4.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](https://github.com/actions/setup-python/compare/v1...v4)

---
updated-dependencies:
- dependency-name: actions/setup-python
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/mpremote.yml

@@ -18,7 +18,7 @@ jobs:
         fetch-depth: '1000'
     - run: |
         git fetch --prune --unshallow --tags
-    - uses: actions/setup-python@v1
+    - uses: actions/setup-python@v4
     - name: Install build tools
       run: pip install build
     - name: Build mpremote wheel