Hide development packages

[djbe]

The latest release 1.1.4 exposes all the development packages in the Package.swift file. You'd think SPM is smart enough to exclude these, but it isn't.

It's creating issues for certain packages that use Komondor (see SwiftGen/StencilSwiftKit#162 (review)), because of dependency conflicts further down (see krzysztofzablocki/Sourcery#1023 (comment)).

The issue was caused by this unhide commit. Normally release commits of Komondor hide these packages again, see for example the release commit for 1.1.3.