Upgrade Ava to v4

node_modules/emittery/package.json

@@ -1,6 +1,6 @@
 {
   "name": "emittery",
-  "version": "0.8.1",
+  "version": "0.10.0",
   "description": "Simple and modern async event emitter",
   "license": "MIT",
   "repository": "sindresorhus/emittery",
@@ -11,7 +11,7 @@
     "url": "https://sindresorhus.com"
   },
   "engines": {
-    "node": ">=10"
+    "node": ">=12"
   },
   "scripts": {
     "test": "xo && nyc ava && tsd"
@@ -48,13 +48,13 @@
     "typed"
   ],
   "devDependencies": {
-    "@types/node": "^13.7.5",
+    "@types/node": "^15.6.1",
     "ava": "^2.4.0",
     "delay": "^4.3.0",
     "nyc": "^15.0.0",
     "p-event": "^4.1.0",
-    "tsd": "^0.14.0",
-    "xo": "^0.36.1"
+    "tsd": "^0.16.0",
+    "xo": "^0.39.0"
   },
   "nyc": {
     "reporter": [