jenkins: skip ubuntu1804-arm64 on Node.js >=21

We already have coverage for Ubuntu 20.04.

Refs: nodejs#3317

Author: targos

jenkins/scripts/VersionSelectorScript.groovy

@@ -35,6 +35,7 @@ def buildExclusions = [
   [ /^centos7-ppcle/,                 anyType,     gte(18) ],
 
   // ARM  --------------------------------------------------
+  [ /^ubuntu1804-arm64/,                             anyType, gte(21) ],
   [ /^cross-compiler-ubuntu1604-armv[67]-gcc-4.9/,   anyType, gte(16) ],
   [ /^cross-compiler-ubuntu1604-armv[67]-gcc-6/,     anyType, gte(16) ],
   [ /^cross-compiler-ubuntu1804-armv7-gcc-6/,        anyType, gte(16) ],