Fixed entrypoint handling for images built with Google Cloud Buildpacks

[sl0wik]

After running multiple tests I couldn't make entrypoint to work with images generated using buildpacks while quoted. After removing this quote everything works correctly.

Quoted version will always throw error like:

docker: Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: exec: "\"launcher\"": executable file not found in $PATH: unknown.