Add docker build workflow

.github/workflows/docker-build.yml

@@ -0,0 +1,50 @@
+name: Docker Build
+
+on:
+    push:
+        branches:
+            - master
+
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        strategy:
+            matrix:
+                include:
+                    - dockerfile: amd64.Dockerfile
+                      platform: linux/amd64
+                    - dockerfile: arm32v7.Dockerfile
+                      platform: linux/arm/v7
+                    - dockerfile: arm64v8.Dockerfile
+                      platform: linux/arm64/v8
+
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@v3
+
+            - name: Set up QEMU
+              uses: docker/setup-qemu-action@v1
+              with:
+                  platforms: all
+
+            - name: Set up Docker Buildx
+              uses: docker/setup-buildx-action@v1
+
+            - name: Login to GitHub Container Registry
+              uses: docker/login-action@v1
+              with:
+                  registry: ghcr.io
+                  username: ${{ github.repository_owner }}
+                  password: ${{ secrets.GITHUB_TOKEN }}
+
+            - name: Build and push
+              uses: docker/build-push-action@v2
+              with:
+                  context: .
+                  file: ./${{ matrix.dockerfile }}
+                  platforms: ${{ matrix.platform }}
+                  push: true
+                  build-args: |
+                      GIT_COMMIT=${{ github.sha }}
+                      CONFIGURATION_NAME=Altcoins-Release
+                  tags: ghcr.io/${{ github.repository_owner }}/btcpayserver:latest