fix: update Docker build to target amd64 architecture only (#19)

Targeting only the amd64 architecture simplifies the Docker build
process by removing support for multi-platform builds across the
backend, caddy, and frontend images. Additionally, an obsolete release
workflow file has been removed.

Author: radumalica

.github/workflows/version-and-release.yml

@@ -95,7 +95,7 @@ jobs:
           context: ./backend
           file: ./backend/Dockerfile
           push: true
-          platforms: linux/amd64,linux/arm64
+          platforms: linux/amd64
           tags: ${{ steps.meta-backend.outputs.tags }}
           labels: ${{ steps.meta-backend.outputs.labels }}
           cache-from: type=registry,ref=ghcr.io/${{ github.repository_owner }}/caddymanager-backend:buildcache
@@ -119,7 +119,7 @@ jobs:
           context: ./caddy
           file: ./caddy/Dockerfile
           push: true
-          platforms: linux/amd64,linux/arm64
+          platforms: linux/amd64
           tags: ${{ steps.meta-caddy.outputs.tags }}
           labels: ${{ steps.meta-caddy.outputs.labels }}
           cache-from: type=registry,ref=ghcr.io/${{ github.repository_owner }}/caddymanager-caddy:buildcache
@@ -143,7 +143,7 @@ jobs:
           context: ./frontend
           file: ./frontend/Dockerfile
           push: true
-          platforms: linux/amd64,linux/arm64
+          platforms: linux/amd64
           tags: ${{ steps.meta-frontend.outputs.tags }}
           labels: ${{ steps.meta-frontend.outputs.labels }}
           cache-from: type=registry,ref=ghcr.io/${{ github.repository_owner }}/caddymanager-frontend:buildcache