Fix docker file

[Luv-Ray]

error when I run make build_docker:

Step 8/13 : COPY --from=build_qemu /usr/local/bin/* /usr/local/bin
When using COPY with more than one source file, the destination must be a directory and end with a /
make: *** [Makefile:8: build_docker] Error 1

docker version:

docker --version
Docker version 27.1.1, build 63125853e3

Adding / after /usr/local/bin fixes it.