add gha workflow for docker image

.github/workflows/docker.yml

@@ -0,0 +1,47 @@
+name: Docker 🐳
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+      - 'v?[0-9]+.[0-9]+.[0-9]+'
+    tags:
+      - "v[0-9]+.[0-9]+.[0-9]+"
+env:
+  GIT_LFS_SKIP_SMUDGE: 1
+permissions:
+  id-token: read
+  contents: read
+  packages: write
+jobs:
+  docker:
+    runs-on: alpine-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+      #- name: Set up QEMU
+        #uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository_owner }}/namada-for-undexer
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and Push docker image
+        uses: docker/build-push-action@v3
+        with:
+          context: .
+          file: Dockerfile
+          push: true
+          labels: ${{ steps.meta.outputs.labels }}
+          tags: ${{ steps.meta.outputs.tags }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max