Add previous_version input for mixed-version tests

Author: mkuratczyk

.github/workflows/test-make-target.yaml

@@ -15,6 +15,10 @@ on:
         required: false
         default: false
         type: boolean
+      previous_version:
+        required: false
+        default: 'tags/v4.0.9'
+        type: string
       make_target:
         required: true
         type: string
@@ -62,7 +66,7 @@ jobs:
       uses: dsaltares/fetch-gh-release-asset@master
       if: inputs.mixed_clusters
       with:
-        version: 'tags/v4.0.9'
+        version: ${{ inputs.previous_version }}
         regex: true
         file: "rabbitmq-server-generic-unix-\\d.+\\.tar\\.xz"
         target: ./