Added Sinhala Language Support (si) (si LK)

[SrilalS]

Is your pull request related to a problem? Please describe

57

I have Added Sinhala Language Support (si) (si LK).

Checklist

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.
• [x] The title of my pull request is a short description of the requested changes.
• [ ] I have added the label enhancement to my pull request.

[elinguiuriel]

@SrilalS test your language at https://m.me/OpenSourceChatbot it seems to work well! 👍