bump checkout from v3 to v4

Author: jnyrup

.github/workflows/build.yml

@@ -11,7 +11,7 @@ jobs:
       DOTNET_NOLOGO: true
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       with:
         fetch-depth: 0
 
@@ -55,7 +55,7 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       with:
         fetch-depth: 0