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/tests.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python 3.8
       uses: actions/setup-python@v2
       with:
@@ -35,7 +35,7 @@ jobs:
     runs-on: ubuntu-latest
     #needs: [lint]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python 3.8
       uses: actions/setup-python@v2
       with:
@@ -129,7 +129,7 @@ jobs:
 
     steps:
     - name: Checkout source
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     # Configure compilers for Windows 64bit.
     - name: Enable MSVC 64bit
@@ -262,7 +262,7 @@ jobs:
     needs: [build_and_test_wheels, build_and_test_sdist]
     steps:
       - name: Checkout source
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Download wheels and sdist
         uses: actions/download-artifact@v2
@@ -322,7 +322,7 @@ jobs:
     needs: [build_and_test_wheels, build_and_test_sdist]
     steps:
       - name: Checkout source
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Download wheels and sdist
         uses: actions/download-artifact@v2