Use kubebuilder action from main

As it is (v0.0.4), it runs into the hard deprecation in GitHub Actions
of add_path.

Signed-off-by: Michael Bridgen <[email protected]>

Author: squaremo

.github/workflows/build.yaml

@@ -24,8 +24,7 @@ jobs:
       with:
         go-version: 1.15.x
     - name: Set up kubebuilder
-      # TODO replace with ../pkg/.. when that's merged
-      uses: fluxcd/pkg/actions/[email protected]
+      uses: fluxcd/pkg/actions/kubebuilder@main
     - name: Run tests
       run: make test
       env: