Bump version to 1.22.0

Bump version to 1.21.0

Bump version to 1.20.0

Bump version to 1.19.0

Merge pull request nix-community#349 from nlewo/release-1.18.0

Bump version to 1.18.0

Bump version to 1.17.1

Bump version number to 1.17.0

Bump version to 1.16.1

Add .0 suffix to version for consistency with previous releases

Bump version to 1.15.5