Bump version to 0.20.1.
Bump version to 0.20.1.

Changes:

* Unbreak omnibus and chain packagers. (#69)

ryansch/fpm-cookery,glensc/fpm-cookery,kisoku/fpm-cookery,devkid/fpm-cookery,ryansch/fpm-cookery,kisoku/fpm-cookery,cas-ei/fpm-cookery,cas-ei/fpm-cookery,glensc/fpm-cookery,devkid/fpm-cookery