build: add GOARCH env to go build

Dockerfile

@@ -19,11 +19,13 @@ COPY --from=templ-stage /templ /tailwind
 RUN npx tailwindcss -i ./input.css -o ./public/css/style.css --minify
 
 # Go build
-FROM golang:alpine AS build-stage
+FROM --platform=$BUILDPLATFORM golang:alpine AS build-stage
+ARG TARGETOS
+ARG TARGETARCH
 RUN apk add --no-cache --update go gcc g++
 COPY --from=tailwind-stage /tailwind /app
 WORKDIR /app
-RUN CGO_ENABLED=1 GOOS=linux go build -o /app/main -buildvcs=false
+RUN CGO_ENABLED=1 GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -o /app/main -buildvcs=false
 
 # Go test
 FROM build-stage AS test-stage