ci: auto build docker image

Dockerfile

@@ -0,0 +1,14 @@
+FROM alpine:edge as builder
+LABEL stage=go-builder
+WORKDIR /app/
+COPY ./ ./
+RUN apk add --no-cache bash git go gcc musl-dev curl; \
+    bash build.sh release docker
+
+FROM alpine:edge
+LABEL MAINTAINER="i@nn.ci"
+VOLUME /opt/alist/data/
+WORKDIR /opt/alist/
+COPY --from=builder /app/bin/alist ./
+EXPOSE 5244
+CMD [ "./alist", "server --no-prefix" ]