ignition-fuel-tools4 4.2.1 (#1104)
ignition-fuel-tools4 4.2.1 (#1104)

* ignition-fuel-tools4: update 4.2.1

* update tarball sha256

Co-authored-by: Steve Peters <19cdd629ec3b4ea4663c77a4169548f370fdc02f@openrobotics.org>
osrf/homebrew-simulation,j-rivero/homebrew-simulation,scpeters/homebrew-simulation