Bump actions/checkout from 2 to 3.1.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 3.1.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v3.1.0)

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

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

Author: dependabot[bot]

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
         platform: [ubuntu-latest, macos-latest, windows-latest]
         python-version: [3.6, 3.9]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3.1.0
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2.3.2
       with:
@@ -42,7 +42,7 @@ jobs:
         python-version: [3.9]
         tasks: [lint, safety, metric, doc, release]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3.1.0
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2.3.2
       with:
@@ -65,7 +65,7 @@ jobs:
     name: Publish release
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3.1.0
     - name: Set up Python
       uses: actions/setup-python@v2.3.2
       with:

.github/workflows/deploy.yml

@@ -11,7 +11,7 @@ jobs:
     name: Deploy to PyPI test server
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3.1.0
     - name: Set up Python
       uses: actions/setup-python@v2.3.2
       with:
@@ -35,7 +35,7 @@ jobs:
     name: Deploy to PyPI
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3.1.0
     - name: Set up Python
       uses: actions/setup-python@v2.3.2
       with:

.github/workflows/docs.yml

@@ -11,7 +11,7 @@ jobs:
     name: Create docs for GitHub Pages 
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3.1.0
     - name: Set up Python 3.9
       uses: actions/setup-python@v2.3.2
       with: