Update linter for ES2022 syntax

Allow modern JavaScript syntax including class property declarations
since Node.js v12 supports this.

.eslintrc.js

@@ -6,10 +6,7 @@ module.exports = {
 	"env": {
 		"node": true,
 		"commonjs": true,
-		"es6": true,
-	},
-	"parserOptions": {
-		"ecmaVersion": 11,
+		"es2022": true,
 	},
 
 	"overrides": [

package.json

@@ -25,7 +25,7 @@
     "@clusterio/lib": "workspace:*",
     "@clusterio/master": "workspace:*",
     "@clusterio/slave": "workspace:*",
-    "eslint": "^7.25.0",
+    "eslint": "^8.18.0",
     "eslint-plugin-node": "^11.1.0",
     "express": "^4.16.2",
     "form-data": "^4.0.0",