Update GitRepository Receiver, and Kustomization to v1

Signed-off-by: Somtochi Onyekwere <somtochionyekwere@gmail.com>

cmd/flux/testdata/export/git-repo.yaml

@@ -1,11 +1,10 @@
 ---
-apiVersion: source.toolkit.fluxcd.io/v1beta2
+apiVersion: source.toolkit.fluxcd.io/v1
 kind: GitRepository
 metadata:
   name: flux-system
   namespace: {{ .fluxns }}
 spec:
-  gitImplementation: go-git
   interval: 5m0s
   ref:
     branch: main