- Moving the `mm:refc` configuration to the main `config.nims` file
makes it be used in tests and tasks that build examples.
- It's not clear why `skipParentCfg`was being used and it doesn't seem
to be necessary.
This PR enables Nim 2.0.x with `refc` garbage collector on CI.
The following compilation error had to be fixed: Error: undeclared
identifier: 'acceptHandler`gensym435'; if declared in a template, this
identifier may be inconsistently marked inject or gensym