Replace no longer maintained uglify-es with terser

See mishoo/UglifyJS#3156 (comment)

package.json

@@ -27,8 +27,8 @@
     "do-test": "mkdir -p http:; ln -nsf .. http://dummyhost; $TESTRUNNER 'test/**/*-test.js'",
     "report": "nyc report --reporter=lcov",
     "coverage": "nyc report --reporter=text-lcov > coverage.lcov && codecov",
-    "prepublishOnly": "npm run build && uglifyjs build/d3-graphviz.js -c -m -o build/d3-graphviz.min.js",
-    "prepublishOnlyOriginal": "env NODE_ENV=production npm run build && TESTRUNNER='tape' npm run do-test && uglifyjs build/d3-graphviz.js -c -m -o build/d3-graphviz.min.js",
+    "prepublishOnly": "npm run build && terser build/d3-graphviz.js -c -m -o build/d3-graphviz.min.js",
+    "prepublishOnlyOriginal": "env NODE_ENV=production npm run build && TESTRUNNER='tape' npm run do-test && terser build/d3-graphviz.js -c -m -o build/d3-graphviz.min.js",
     "publicbuild": "env NODE_ENV=production npm run build",
     "postpublish": "zip -j build/d3-graphviz.zip -- LICENSE README.md build/d3-graphviz.js build/d3-graphviz.min.js"
   },
@@ -57,8 +57,8 @@
     "rollup": "0.46.0",
     "rollup-plugin-babel": "^3.0.3",
     "tape": "^4.9.0",
-    "tiny-worker": "^2.1.2",
-    "uglify-es": "^3.0.27"
+    "terser": "^4.6.6",
+    "tiny-worker": "^2.1.2"
   },
   "dependencies": {
     "@hpcc-js/wasm": "^0.3.8",