Drop myself from owners of genobject (#96216)

Author: 1st1

.github/CODEOWNERS

@@ -9,7 +9,7 @@
 
 # Core
 **/*context* @1st1
-**/*genobject* @1st1 @markshannon
+**/*genobject* @markshannon
 **/*hamt* @1st1
 Objects/set* @rhettinger
 Objects/dict* @methane @markshannon