fix(docker): build push gateway without --locked after cargo chef cook

Same cargo chef cook lock divergence as the relay Dockerfile; build without
--locked so the lock is refreshed to the chef resolution.

Closes #18 (part 12 docker)

Signed-off-by: Brian Charbonneau <github@briancharbonneau.com>

Author: BrianInAz

Dockerfile.push-gateway

@@ -17,7 +17,9 @@ RUN apt-get update \
 COPY --from=planner /build/recipe.json recipe.json
 RUN cargo chef cook --release --recipe-path recipe.json
 COPY . .
-RUN cargo build --release --locked -p buzz-push-gateway --bin buzz-push-gateway \
+# cargo chef cook resolves workspace crates to recipe versions that diverge
+# from the committed lock; --locked would then fail. Build without it.
+RUN cargo build --release -p buzz-push-gateway --bin buzz-push-gateway \
     && strip target/release/buzz-push-gateway
 
 FROM debian:${DEBIAN_VERSION}-slim AS runtime