prosilica_driver: 1.9.4-0 in 'hydro/distribution.yaml' [bloom]

Increasing version of package(s) in repository `prosilica_driver` to `1.9.4-0`:

- upstream repository: https://github.com/ros-drivers/prosilica_driver.git
- release repository: https://github.com/ros-drivers-gbp/prosilica_driver-release.git
- distro file: `hydro/distribution.yaml`
- bloom version: `0.5.11`
- previous version for package: `1.9.3-0`