Add kustomize-version input with working (5.1.1) default (#9)

Add kustomize-version input with 5.1.1 default

There is an error with the archive format as part of the 5.2.0 release that is causing all our deployment builds to fail.

kubernetes-sigs/kustomize#5396

Initial approach didn't work with GHA variables so we'll use a new input but default its value for backwards compatibility.

action.yml

@@ -27,12 +27,16 @@ inputs:
     description: 'A comma or newline separated list of labels.'
     required: true
     default: "automerge"
+  kustomize-version:
+    description: 'The kustomize version as allowed by the setup-kustomize action.'
+    required: true
+    default: "5.1.1"
 runs:
   using: "composite"
   steps:
     - uses: imranismail/setup-kustomize@v2
       with:
-        kustomize-version: ${{ vars.UPDATE_IMAGE_TAG_ACTION_KUSTOMIZE_VERSION || '5.1.1' }}
+        kustomize-version: ${{ inputs.kustomize-version }}
 
     - name: Checkout
       uses: actions/checkout@v3