Feature:: Add multi-arch docker image

Resolves #2

.dockerignore

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+/node_modules
+/mailpit

.github/workflows/build-docker.yml

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+on:
+  release:
+    types: [created]
+
+name: Build docker images
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    - name: Get tag
+      id: tag
+      uses: dawidd6/action-get-tag@v1
+
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v2
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v2
+
+    - name: Login to DockerHub
+      uses: docker/login-action@v2
+      with:
+        username: ${{ secrets.DOCKER_USERNAME }}
+        password: ${{ secrets.DOCKER_ACCESS_TOKEN }}
+
+    - name: Build and push
+      uses: docker/build-push-action@v3
+      with:
+        context: .
+        platforms: linux/amd64,linux/arm64,linux/arm
+        build-args: |
+          "VERSION=${{ steps.tag.outputs.tag }}"
+        push: true
+        tags: axllent/mailpit:latest,axllent/mailpit:${{ steps.tag.outputs.tag }}

Dockerfile

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+FROM golang:alpine as builder
+
+ARG VERSION=dev
+
+COPY . /app
+
+WORKDIR /app
+
+RUN apk add --no-cache git npm && \
+npm install && npm run package && \
+CGO_ENABLED=0 go build -ldflags "-s -w -X github.com/axllent/mailpit/cmd.Version=${VERSION}" -o /mailpit
+
+
+FROM alpine:latest
+
+COPY --from=builder /mailpit /mailpit
+
+RUN apk add --no-cache tzdata
+
+ENTRYPOINT ["/mailpit"]