fix minor bug in synth settings ring

[seanbudd]

Link to issue number:

None

Summary of the issue:

_set_currentSettingValue had invalid syntax, with two symbols not being referenced correctly
The function is currently not used in NVDA core, so the bug went unnoticed

Description of user facing changes

None

Description of development approach

Use correct references for symbols.

linting and typing fixes

Testing strategy:

None

Known issues with pull request:

None

Code Review Checklist:

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

[AppVeyorBot]

• PASS: Translation comments check.
• PASS: Unit tests.
• FAIL: Lint check. See test results for more information.
• PASS: System tests (tags: installer NVDA).
• Build (for testing PR): https://ci.appveyor.com/api/buildjobs/cjayst5iyom4etry/artifacts/output/nvda_snapshot_pr16153-30999,5e723f35.exe
• CI timing (mins):
  INIT 0.0,
  INSTALL_START 1.0,
  INSTALL_END 0.9,
  BUILD_START 0.0,
  BUILD_END 28.1,
  TESTSETUP_START 0.0,
  TESTSETUP_END 0.3,
  TEST_START 0.0,
  TEST_END 2.3,
  FINISH_END 0.2

See test results for failed build of commit 5e723f35c5