Notify Sviat of GHA changes through codeowners (python#143945)

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: webknjaz

.github/CODEOWNERS

@@ -63,8 +63,8 @@
 .azure-pipelines/             @AA-Turner
 
 # GitHub & related scripts
-.github/                               @ezio-melotti @hugovk @AA-Turner
-Tools/build/compute-changes.py         @AA-Turner
+.github/                               @ezio-melotti @hugovk @AA-Turner @webknjaz
+Tools/build/compute-changes.py         @AA-Turner @hugovk @webknjaz
 Tools/build/verify_ensurepip_wheels.py @AA-Turner @pfmoore @pradyunsg
 
 # Pre-commit