fix issue of building docker image (#563)

Author: DuodenumL

.github/workflows/dockerimage.yml

@@ -13,6 +13,8 @@ jobs:
     steps:
       - name: checkout
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
 
       - name: build and push to github packages
         uses: docker/build-push-action@v1

Dockerfile

@@ -2,7 +2,7 @@ FROM golang:alpine AS BUILD
 
 # make binary
 RUN apk add --no-cache build-base musl-dev git curl make cmake
-RUN git clone https://github.com/projecteru2/core.git /go/src/github.com/projecteru2/core
+COPY . /go/src/github.com/projecteru2/core
 WORKDIR /go/src/github.com/projecteru2/core
 ARG KEEP_SYMBOL
 RUN make build && ./eru-core --version