Bump actions/checkout from 2 to 3 (#92)

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](https://github.com/actions/checkout/compare/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

@@ -9,7 +9,7 @@ jobs:
   Check_Formatting:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - uses: hecrj/setup-rust-action@v1
       with:
         rust-version: stable
@@ -20,7 +20,7 @@ jobs:
   miri-tests:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - uses: hecrj/setup-rust-action@v1
       with:
         rust-version: nightly
@@ -65,7 +65,7 @@ jobs:
 
     runs-on: ${{ matrix.platform.os }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
 
     # Used to cache cargo-web
     - name: Cache cargo folder