Bump actions/checkout from 6 to 7

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/build-wheels.yml

@@ -40,7 +40,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout FFCx
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           ref: ${{ github.event.inputs.ffcx_ref }}
       - name: Upgrade pip and setuptools

.github/workflows/dolfinx-tests.yml

@@ -24,7 +24,7 @@ jobs:
       PRTE_MCA_rmaps_default_mapping_policy: :oversubscribe   # Newer OpenMPI
       OMPI_MCA_rmaps_base_oversubscribe: true                 # Older OpenMPI
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Load environment variables
         run: cat .github/workflows/fenicsx-refs.env >> $GITHUB_ENV
       - name: Install UFL and Basix
@@ -35,7 +35,7 @@ jobs:
         run: |
           pip3 install --break-system-packages .
       - name: Get DOLFINx source
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           path: ./dolfinx
           repository: ${{ env.dolfinx_repository }}

.github/workflows/pythonapp.yml

@@ -51,7 +51,7 @@ jobs:
             -Source "${{ env.FEED_URL }}"
 
       - name: Checkout FFCx
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Load environment variables (Unix)
         if: runner.os != 'Windows'
@@ -146,7 +146,7 @@ jobs:
 
       - name: Checkout FEniCS/docs
         if: ${{ github.repository == 'FEniCS/ffcx' && ( github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/') ) && runner.os == 'Linux' && matrix.python-version == 3.12 }}
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           repository: "FEniCS/docs"
           path: "docs"

.github/workflows/spack.yml

@@ -35,7 +35,7 @@ jobs:
           apt-get install -y g++ gfortran  # compilers
 
       - name: Get Spack
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           path: ./spack
           repository: spack/spack