CI: upgrade actions to latest

checkout@v5, setup-go@v6

Author: dolmen

.github/workflows/go.yml

@@ -14,10 +14,10 @@ jobs:
     steps:
 
     - name: Check out code
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
 
     - name: Set up Go
-      uses: actions/setup-go@v4
+      uses: actions/setup-go@v6
       with:
         go-version: ${{ matrix.go }}
       id: go