fix: Added missing interface definition

Current version of the nest-emitter library is incompatible with Node 12
typings, this adds a required interface manually as hotfix. A new
version of the lib will hopefully be released soon.

typings/node/index.d.ts

@@ -0,0 +1,4 @@
+declare namespace NodeJS {
+    // drop-in hotfix for nest-emitter on Node 12, awaiting new version
+    export interface Events extends EventEmitter {}
+}