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/deploy_docs.yaml

@@ -10,7 +10,7 @@ jobs:
     name: Deploy docs
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Install python 3.7
         uses: actions/setup-python@v3

.github/workflows/release_pypi.yaml

@@ -11,7 +11,7 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Set up Python
         uses: actions/setup-python@v3
         with:

.github/workflows/test.yaml

@@ -15,7 +15,7 @@ jobs:
     name: Unit test
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Install python 3.7
         uses: actions/setup-python@v3
@@ -63,7 +63,7 @@ jobs:
     name: Formatting check
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           # Full git history is needed to get a proper list of changed test_files within `super-linter`
           fetch-depth: 0
@@ -88,7 +88,7 @@ jobs:
     name: Test docs
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Install python 3.7
         uses: actions/setup-python@v3