Reverse dependencies for rapngasm

Latest version of the following gems require rapngasm

Gem	Version	Date	Downloads
phantom_svg +60.7 Thousand Downloads	`1.2.8` March 16, 2018	March 16, 2018	60.7 Thousand
emojidex-converter +42.3 Thousand Downloads	`0.4.1` July 04, 2017	July 04, 2017	42.3 Thousand
apngasm +6.04 Thousand Downloads	`3.0.0` February 04, 2014	February 04, 2014	6.04 Thousand
apngasm-gui +4.83 Thousand Downloads	`0.0.1` May 21, 2014	May 21, 2014	4.83 Thousand