upgrade node version to >18 (#1220)

Author: wboereboom

.github/workflows/nodejs.yml

@@ -9,7 +9,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [14.x, 16.x, 18.x]
+        node-version: [18.x, 20.x]
 
     steps:
     - uses: actions/checkout@v3

README.md

@@ -53,7 +53,7 @@ Before you begin to integrate:
 
 - [Create an Adyen test account](https://docs.adyen.com/get-started-with-adyen#test-account).
 - [Set up your API credentials](https://docs.adyen.com/development-resources/api-credentials).
-- [Install Node.js](https://nodejs.org/en/download/) version 12 or later.
+- [Install Node.js](https://nodejs.org/en/download/) version 18 or later.
 
 ## Installation
 

package.json

@@ -5,7 +5,7 @@
   "main": "lib/src/index.js",
   "types": "lib/src/index.d.ts",
   "engines": {
-    "node": ">=12"
+    "node": ">=18"
   },
   "repository": {
     "type": "git",