Bump actions/checkout from 2 to 3

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>

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         SCALA_VERSION: ["2.12.15", "2.13.8"]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
       with:
         fetch-depth: 0
         submodules: true
@@ -32,7 +32,7 @@ jobs:
     if: github.event_name == 'push'
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
       with:
         fetch-depth: 0
         submodules: true