chore: bump actions/checkout from 2 to 3 (#507)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v3)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/coder-test-stability.yaml

@@ -39,7 +39,7 @@ jobs:
           - 1
           - 2
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - uses: actions/setup-go@v2
         with:

.github/workflows/coder.yaml

@@ -308,7 +308,7 @@ jobs:
           # https://github.com/coder/coder/issues/384
           # - windows-2022
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Cache Node
         id: cache-node