github: Add llvm-reduce to PR autolabeler (#141335)

diff --git a/.github/new-prs-labeler.yml b/.github/new-prs-labeler.yml
index 69ba47a..94e33df 100644
--- a/.github/new-prs-labeler.yml
+++ b/.github/new-prs-labeler.yml
@@ -709,6 +709,9 @@
   - llvm/test/tools/llvm-exegesis/**
   - llvm/unittests/tools/llvm-exegesis/**
 
+tools:llvm-reduce:
+  - llvm/tools/llvm-reduce/**
+
 platform:windows:
   - lld/COFF/**
   - clang/lib/Driver/MSVC.cpp