Bump version to 0.26.1.
Bump version to 0.26.1.

* Revert "Avoid using git ls-files in gemspec".

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