Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
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/continuous-integration.yml

@@ -38,7 +38,7 @@ jobs:
       run:  echo 127.0.0.1 `hostname` | sudo tee -a /etc/hosts > /dev/null
 
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Setup MPI (${{ matrix.mpi }})
       uses: mpi4py/setup-mpi@v1
@@ -95,7 +95,7 @@ jobs:
     steps:
 
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Use Python ${{ matrix.py }}
       uses: actions/setup-python@v4

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
     steps:
 
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Setup Python
       uses: actions/setup-python@v4