Build docker image when a tag is pushed

.github/workflows/docker-image-build.yaml

@@ -1,22 +1,20 @@
 name: build and push image to dockerhub
 on:
   push:
-    branches:
-      - ona-custom-changes
-  workflow_dispatch:
-    inputs:
-      versionTag:
-        description: "Version Tag"
-        required: true
-        default: ""
+    tags:
+      - '[0-9]+\.[0-9]+\.[0-9]+'
 jobs:
   main:
     runs-on: ubuntu-22.04
     steps:
+      - name: Get the version
+        id: get-version-release
+        run: echo "version=${GITHUB_REF_NAME#refs/heads}" >> $GITHUB_ENV
+
       - name: Checkout to version
         uses: actions/checkout@v3
         with:
-          ref: ${{ github.event.inputs.versionTag || '0.0.4' }}
+          ref: ${{ env.version }}
 
       - name: Login to DockerHub
         uses: docker/login-action@v2
@@ -32,7 +30,7 @@ jobs:
           file: Dockerfile
           platforms: linux/amd64
           tags: |
-            onaio/dirt-tile-server:${{ github.event.inputs.versionTag || '0.0.4' }}
+            onaio/dirt-tile-server:${{ env.version }}
 
       - name: Image digest
         run: echo ${{ steps.docker-build.outputs.digest }}