chore(deps): update actions/checkout action to v4 (#176)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/merge.yml

@@ -19,7 +19,7 @@ jobs:
       image: ${{ matrix.container }}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: recursive
 

.github/workflows/pullrequest.yml

@@ -22,7 +22,7 @@ jobs:
       image: ${{ matrix.container }}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: recursive
 

.github/workflows/release.yml

@@ -39,7 +39,7 @@ jobs:
       image: "python:3.11"
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Cache virtualenvironment
         uses: actions/cache@v3