Bump terser from 4.1.4 to 4.8.1 in /src

Bumps [terser](https://github.com/terser/terser) from 4.1.4 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>

src/package-lock.json

@@ -6015,9 +6015,9 @@
       }
     },
     "terser": {
-      "version": "4.1.4",
-      "resolved": "https://registry.npmjs.org/terser/-/terser-4.1.4.tgz",
-      "integrity": "sha512-+ZwXJvdSwbd60jG0Illav0F06GDJF0R4ydZ21Q3wGAFKoBGyJGo34F63vzJHgvYxc1ukOtIjvwEvl9MkjzM6Pg==",
+      "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",