ci: add image build workflow.

The workflow needs the $TAG variable to be used as the image tag.

Author: gustavosr8

.github/workflows/build.yml

@@ -0,0 +1,13 @@
+name: Build image
+on:
+  push:
+    tags:
+      - 'v*'
+  pull_request:
+
+jobs:
+  build_and_push:
+    permissions:
+      packages: write
+      contents: read
+    uses: cnpem/epics-in-docker/.github/workflows/ioc-images.yml@main

docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   ioc:
-    image: ghcr.io/cnpem/hvps-epics-ioc:latest
+    image: ghcr.io/cnpem/hvps-epics-ioc:$TAG
     build:
       context: ./
       dockerfile: docker/Dockerfile