Drop repo's 'crystallang' and 'crystal-language' topics

[matiasgarciaisaia]

The Crystal community has somewhat decided to use crystal as the language's topic.

To avoid fragmentation in the community, please drop crystallang and crystal-language topics, that only have ~12 or ~28 repositories at the moment. We're sticking to crystal, instead.

Any contributor can change it from the repo's homepage.

See crystal-lang/crystal#4241 for more context.

Thank you very much :)

[Givralix]

Done! Thanks