fix: missing BIN arg

Author: lherman-cs

Dockerfile

@@ -1,6 +1,5 @@
 FROM docker.io/library/rust:1.84-alpine AS builder
 
-ARG BIN=pulsebeam-server-lite
 RUN apk add make protobuf-dev musl-dev
 WORKDIR /app
 
@@ -12,14 +11,12 @@ RUN --mount=type=cache,target=/app/target/ \
     --mount=type=cache,target=/usr/local/cargo/registry/ \
     --mount=type=cache,target=/root/.cargo/git \
     --mount=type=cache,target=/root/.cargo/registry \
-    cargo build --release && \
-    # Copy executable out of the cache so it is available in the final image.
-    cp target/release/${BIN} ./${BIN}
+    cargo build --release
 
 FROM docker.io/library/alpine:3
 
 WORKDIR /app
-COPY --from=builder /app/${BIN} .
+COPY --from=builder /app/target/release/pulsebeam-server-lite .
 
 ENTRYPOINT ["./server-rs"]