Revert "docker: Change ENTRYPOINT to CMD (#1943)"

This reverts commit 1f3aec6.

Author: kyleconroy

Dockerfile

@@ -16,4 +16,4 @@ RUN go run scripts/release.go -docker
 FROM scratch
 
 COPY --from=builder /workspace/sqlc /workspace/sqlc
-CMD ["/workspace/sqlc"]
+ENTRYPOINT ["/workspace/sqlc"]