workflows: Use latest version of actions/checkout

It isn't entirely clear to me what the incompatibilities are, but
hopefully in simple cases like ours it's functionally equivalent.

Signed-off-by: Simon McVittie <smcv@collabora.com>

.github/workflows/check.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Check out
-      uses: actions/checkout@v1
+      uses: actions/checkout@v4
     - name: Install build-dependencies
       run: sudo ./ci/builddeps.sh
     - name: Create logs dir
@@ -89,7 +89,7 @@ jobs:
       with:
         languages: ${{ matrix.language }}
     - name: Check out
-      uses: actions/checkout@v1
+      uses: actions/checkout@v4
     - name: Install build-dependencies
       run: sudo ./ci/builddeps.sh --clang
     - run: meson build -Dselinux=enabled