Reverse dependencies for packable

Latest version of the following gems require packable

Gem	Version	Date	Downloads
daru +3.37 Million Downloads	`0.3` May 30, 2020	May 30, 2020	3.37 Million
nmatrix +145 Thousand Downloads	`0.2.4` December 14, 2017	December 14, 2017	145 Thousand
flvedit +37.7 Thousand Downloads	`0.7.4` September 24, 2009	September 24, 2009	37.7 Thousand
marcandre-flvedit +26.1 Thousand Downloads	`0.7.3` August 11, 2014	August 11, 2014	26.1 Thousand