[github] Add myself as default code reviewer (#89099)

Author: grypp

.github/CODEOWNERS

@@ -113,7 +113,7 @@ clang/test/AST/Interp/ @tbaederr
 
 # MLIR NVVM Dialect in MLIR
 /mlir/**/LLVMIR/**/BasicPtxBuilderInterface* @grypp
-/mlir/**/NVVM*/ @grypp
+/mlir/**/NVVM* @grypp
 
 # MLIR Python Bindings
 /mlir/test/python/ @makslevental @stellaraccident