Bump terser from 4.4.0 to 4.8.1 in /arbortect

Bumps [terser](https://github.com/terser/terser) from 4.4.0 to 4.8.1.
- [Release notes](https://github.com/terser/terser/releases)
- [Changelog](https://github.com/terser/terser/blob/master/CHANGELOG.md)
- [Commits](https://github.com/terser/terser/commits)

---
updated-dependencies:
- dependency-name: terser
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

arbortect/package-lock.json

@@ -5124,9 +5124,9 @@
       "dev": true
     },
     "terser": {
-      "version": "4.4.0",
-      "resolved": "https://registry.npmjs.org/terser/-/terser-4.4.0.tgz",
-      "integrity": "sha512-oDG16n2WKm27JO8h4y/w3iqBGAOSCtq7k8dRmrn4Wf9NouL0b2WpMHGChFGZq4nFAQy1FsNJrVQHfurXOSTmOA==",
+      "version": "4.8.1",
+      "resolved": "https://registry.npmjs.org/terser/-/terser-4.8.1.tgz",
+      "integrity": "sha512-4GnLC0x667eJG0ewJTa6z/yXrbLGv80D9Ru6HIpCQmO+Q4PfEtBFi0ObSckqwL6VyQv/7ENJieXHo2ANmdQwgw==",
       "dev": true,
       "requires": {
         "commander": "^2.20.0",