fix: update ts lib config (#680)

this enables es2019 features plus others already present in node 12

Author: hugomrdias

src/config/tsconfig.aegir.json

@@ -21,9 +21,9 @@
         "resolveJsonModule": true,
         "preserveConstEnums": true,
         "removeComments": false,
-        "target": "ES2018",
+        "target": "ES2019",
         "moduleResolution": "node",
-        "lib": ["ES2018", "DOM"],
+        "lib": ["ES2019", "ES2020.Promise", "ES2020.String", "ES2020.BigInt", "DOM", "DOM.Iterable"],
         "noEmitOnError": true,
         "noEmit": false,
         "emitDeclarationOnly": true,