Missing "Gem::Version" when building from debase source

https://github.com/Speak2Erase/conan-ruby/runs/3539249814?check_suite_focus=true#step:6:2019
(I think the workaround for this would be to add
```rb
require "rubygems/requirement.rb"
require "rubygems/version.rb"
```
to lib/debase/ruby_core_source.rb)