feat(release): setup for publishing docker images to ghcr

Dockerfile

@@ -1,17 +1,5 @@
-FROM golang:1.16-alpine as builder
-RUN apk add --no-cache \
-    git
-
-WORKDIR /app
-COPY . /app
-RUN env CGO_ENABLED=0 \
-    go build -a -o /casecmp -ldflags "-s -w \
-        -X main.version=$(cat VERSION) \
-        -X main.commit=$(git show --format='%h' --no-patch) \
-        -X main.date=$(date +%Y-%m-%dT%T%z)"
-
 FROM scratch
-COPY --from=builder /casecmp /
+COPY ./casecmp /
 ENV PORT 8080
 EXPOSE 8080
 WORKDIR /