Adding Sway Support

Tried to add Sway support

* https://github.com/paul-gauthier/grep-ast/pull/3
    * PR based on https://github.com/paul-gauthier/grep-ast/pull/1

 like  TTL in  https://github.com/paul-gauthier/grep-ast/issues/2 ,
 
and encountered similar error when runnig pytest in docker container, otherwise seems like simple change and https://github.com/FuelLabs/tree-sitter-sway is available.


