[repo] fix: Update CODEOWNERS (#2181)

## Linked issues

closes: #minor

## Details
* Add rajan-chari to CODEOWNERS for JS, .NET, and Python

## Attestation Checklist

- [x] My code follows the style guidelines of this project

- I have checked for/fixed spelling, linting, and other errors
- I have commented my code for clarity
- I have made corresponding changes to the documentation (updating the
doc strings in the code is sufficient)
- My changes generate no new warnings
- I have added tests that validates my changes, and provides sufficient
test coverage. I have tested with:
  - Local testing
  - E2E testing in Teams
- New and existing unit tests pass locally with my changes

.github/CODEOWNERS

@@ -2,15 +2,15 @@
 
 # JS
 
-/js @aacebo @corinagum @lilyydu @singhk97
+/js @aacebo @corinagum @lilyydu @singhk97 @rajan-chari
 
 # .NET
 
-/dotnet @aacebo @corinagum @lilyydu @singhk97
+/dotnet @aacebo @corinagum @lilyydu @singhk97 @rajan-chari
 
 # Python
 
-/python @aacebo @corinagum @lilyydu @singhk97
+/python @aacebo @corinagum @lilyydu @singhk97 @rajan-chari
 
 # TTK