dependabot: implement workaround to run generate go openapi in GOPATH

.github/workflows/dependabot.yml

@@ -19,8 +19,15 @@ jobs:
       with:
         go-version: '1.17'
       id: go
+    # Note: We have to run everything in the GOPATH as `make generate-go-openapi`
+    # currently does not work outside of the GOPATH, see:
+    # https://github.com/kubernetes-sigs/cluster-api/issues/6526
     - name: Check out code into the Go module directory
       uses: actions/checkout@v3
+      with:
+        path: './src/sigs.k8s.io/cluster-api'
+    - name: Set env
+      run:  echo "GOPATH=${GITHUB_WORKSPACE}" >> $GITHUB_ENV
     - uses: actions/[email protected]
       name: Restore go cache
       with:
@@ -32,12 +39,15 @@ jobs:
           ${{ runner.os }}-go-
     - name: Update all modules
       run: make generate-modules
+      working-directory: './src/sigs.k8s.io/cluster-api'
     - name: Update generated code
       run: make generate
+      working-directory: './src/sigs.k8s.io/cluster-api'
     - uses: EndBug/add-and-commit@v9
       name: Commit changes
       with:
         author_name: dependabot[bot]
         author_email: 49699333+dependabot[bot]@users.noreply.github.com
         default_author: github_actor
         message: 'Update generated code'
+        cwd: './src/sigs.k8s.io/cluster-api'