Update sonic to commit 1d70513

[codeofdusk]

Link to issue number:

None

Summary of the issue:

The Sonic library used to speed up eSpeak is many years out of date.

Description of how this pull request fixes the issue:

Updates to latest commit.

Testing strategy:

Verified that rate boost is still functional. Merge early to catch issues before release.

Known issues with pull request:

None known.

Change log entries:

== Changes ==

• Updated Sonic rate boost library to commit 1d70513.

Code Review Checklist:

• Pull Request description:
  • description is up to date
  • change log entries
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• API is compatible with existing add-ons.
• Documentation:
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• Security precautions taken.

[lukaszgo1]

Please update the version of Sonic in the readme.