fix(ci): try speed up docker build

Dockerfile

@@ -6,15 +6,18 @@ ARG BuildTime="Unknown"
 
 WORKDIR /app
 
-COPY . .
+COPY go.mod go.sum ./
+RUN --mount=type=cache,target=/go/pkg/mod \
+    go mod download
 
+COPY . .
 RUN --mount=type=cache,target=/root/.cache/go-build \
     --mount=type=cache,target=/go/pkg \
     CGO_ENABLED=0 \ 
     go build -trimpath \ 
     -ldflags "-s -w \ 
     -X github.com/krau/SaveAny-Bot/common.Version=${VERSION} \
-    -X github.com/krau/SaveAny-Bot/common.GitCommit=${GiTCommit} \
+    -X github.com/krau/SaveAny-Bot/common.GitCommit=${GitCommit} \
     -X github.com/krau/SaveAny-Bot/common.BuildTime=${BuildTime}" \
     -o saveany-bot .