dockerfile: remove gopath override (#42)

move the go install command so that it's called by the build user
instead of root.

running go install with root would lead to some folders in /go/pkg/
being owned by root and not writable by the build user, which eventually
leads to permission errors when building the profiler, specifically to
download new dependencies.

also put /go in a volume which is persisted between consecutive runs,
meaning docker-compose restart will reuse the go cache / go dependencies
speeding up builds for local development.

Dockerfile

@@ -2,12 +2,12 @@ FROM golang:1.23.1-bookworm@sha256:dba79eb312528369dea87532a65dbe9d4efb26439a0fe
 
 RUN apt-get update -y && apt-get upgrade -y && apt-get install -y sudo && apt-get clean autoclean && apt-get autoremove --yes 
 
-RUN go install github.com/golangci/golangci-lint/cmd/[email protected]
-
-ENV GOPATH=
-
 RUN useradd -ms /bin/bash build
 RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers
 RUN adduser build sudo
 
 USER build
+
+RUN go install github.com/golangci/golangci-lint/cmd/[email protected]
+
+VOLUME /go