Fix generating Dockerfile with Gomu (#2254)

Somehow I didn't test this and managed to forget to properly close a
template control structure. This change fixes that.

cmd/gomu/cmd/cli/new/template/docker.go

@@ -5,7 +5,7 @@ var Dockerfile = `FROM golang:alpine AS builder
 ENV CGO_ENABLED=0 GOOS=linux
 WORKDIR /go/src/{{.Alias}}
 RUN apk --update --no-cache add ca-certificates gcc libtool make musl-dev protoc
-COPY {{if not .Client}}Makefile {{end}go.mod go.sum ./
+COPY {{if not .Client}}Makefile {{end}}go.mod go.sum ./
 RUN {{if not .Client}}make init && {{end}}go mod download
 COPY . .
 RUN make {{if not .Client}}proto {{end}}tidy build