Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

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

Author: dependabot[bot]

.github/workflows/autopush.yml

@@ -10,7 +10,7 @@ jobs:
         if: github.repository == 'inducer/pytato'
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v3
+        -   uses: actions/checkout@v4
         -   run: |
                 mkdir ~/.ssh && echo -e "Host gitlab.tiker.net\n\tStrictHostKeyChecking no\n" >> ~/.ssh/config
                 eval $(ssh-agent) && echo "$GITLAB_AUTOPUSH_KEY" | ssh-add -