GitHub actions update setup-go (#881)

This does caching for us, so we can remove our manual caching of modules

.github/workflows/gofmt.yml

@@ -14,21 +14,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-    - name: Set up Go 1.20
-      uses: actions/setup-go@v2
-      with:
-        go-version: "1.20"
-      id: go
+    - uses: actions/checkout@v3
 
-    - name: Check out code into the Go module directory
-      uses: actions/checkout@v2
-
-    - uses: actions/cache@v2
+    - uses: actions/setup-go@v4
       with:
-        path: ~/go/pkg/mod
-        key: ${{ runner.os }}-gofmt1.20-${{ hashFiles('**/go.sum') }}
-        restore-keys: |
-          ${{ runner.os }}-gofmt1.20-
+        go-version-file: 'go.mod'
+        check-latest: true
 
     - name: Install goimports
       run: |