fix: use alpine as base image

Images that do not have ahy shell cannot be used by a Docker executor on GitLab

Author: nhedger

Dockerfile

@@ -20,7 +20,7 @@ RUN tar -xzvf /tmp/biome.tar.gz -C /usr/src/biome/ --strip-components=1
 ENV RUSTFLAGS="-C strip=symbols"
 RUN cargo build -p biome_cli --release
 
-FROM scratch AS biome
+FROM alpine:${ALPINE_VERSION} AS biome
 
 COPY --from=builder /usr/src/biome/target/release/biome /usr/local/bin/biome