Bump actions/checkout from 2 to 3 (#43)

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/ci.yml

@@ -53,7 +53,7 @@ jobs:
         os: [ubuntu-20.04, windows-latest, macos-latest]
         scalaJsVersion: ["1.9.0", "1.10.0", "1.10.1", "1.11.0", "1.12.0", "1.13.0"]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           fetch-depth: 0
           submodules: true
@@ -97,7 +97,7 @@ jobs:
       matrix:
         scalaJsVersion: ["1.9.0", "1.10.0", "1.10.1", "1.11.0", "1.12.0", "1.13.0"]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           fetch-depth: 0
           submodules: true
@@ -131,7 +131,7 @@ jobs:
       matrix:
         scalaJsVersion: ["1.9.0", "1.10.0", "1.10.1", "1.11.0", "1.12.0", "1.13.0"]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           fetch-depth: 0
           submodules: true