build: Switch to build args in Dockerfile

`--env` is a podman-specific feature. While it is clear that podman is a
requirement here, switching these to build arguments better expresses
intent.

 These values are meant to be configurable at build time, which is
 exactly what build arguments are for, while environment variables are
 meant to persist in the image built.

Signed-off-by: Yorgos Saslis <yorgos.work@proton.me>

build/Dockerfile

@@ -4,6 +4,11 @@ LABEL maintainer="Radicle Team <team@radicle.xyz>"
 WORKDIR /src
 COPY . .
 
+ARG TZ
+ARG LC_ALL
+ARG SOURCE_DATE_EPOCH
+ARG RADICLE_VERSION
+
 # Copy cargo configuration we're going to use to specify compiler options.
 RUN mkdir -p .cargo && cp build/config.toml .cargo/config.toml
 # Install dependencies.
@@ -51,6 +56,10 @@ RUN cargo zigbuild --locked --release \
 # Now copy the files to a new image without all the intermediary artifacts to
 # save some space.
 FROM alpine:3.19 as packager
+
+ARG RADICLE_VERSION
+ARG SOURCE_DATE_EPOCH
+
 COPY --from=builder \
      /src/target/x86_64-unknown-linux-musl/release/rad \
      /src/target/x86_64-unknown-linux-musl/release/git-remote-rad \
@@ -84,7 +93,7 @@ RUN find * -maxdepth 0 -type d -exec mv '{}' "radicle-$RADICLE_VERSION-{}" \; &&
     find * -maxdepth 0 -type d -exec tar \
     --sort=name \
     --verbose \
-    --mtime="@$GIT_COMMIT_TIME" \
+    --mtime="@$SOURCE_DATE_EPOCH" \
     --owner=0 \
     --group=0 \
     --numeric-owner \

build/build

@@ -40,12 +40,10 @@ main() {
 
   echo "Building image ($image).."
   podman --cgroup-manager=cgroupfs build \
-    --env SOURCE_DATE_EPOCH \
-    --env TZ \
-    --env LC_ALL \
-    --env GIT_COMMIT_TIME=$SOURCE_DATE_EPOCH \
-    --env GIT_HEAD=$rev \
-    --env RADICLE_VERSION=$version \
+    --build-arg SOURCE_DATE_EPOCH \
+    --build-arg TZ \
+    --build-arg LC_ALL \
+    --build-arg RADICLE_VERSION=$version \
     --arch amd64 --tag $image -f ./build/Dockerfile - < $gitarchive
 
   echo "Creating container (radicle-build-container).."