Fix tree-sitter constants

[sadikovi]

Requirements

• Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• All new code requires tests to ensure against regressions

Description of the Change

This PR fixes syntax highlighting for constants when using tree-sitter. Examples that are fixed now:

d = A1_B2_C3;
e = A1_B2_C$;
f = Test.A1_B2_C3;

Alternate Designs

N/A

Benefits

N/A

Possible Drawbacks

Applicable Issues

Fixes #240