chore: bump ecma version

we transpile to es2017, so allow use of es2020
diff --git a/.eslintrc b/.eslintrc
index 46fb354..276d6ff 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -5,7 +5,7 @@
 		"es6": true
 	},
 	"parserOptions": {
-		"ecmaVersion": 9,
+		"ecmaVersion": 11,
 		"sourceType": "module"
 	},
 	"extends": "eslint:recommended",