Add readme, drop node 18 support

Author: gkwang

Diff for: .github/workflows/test.yml

@@ -23,7 +23,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [ 12, 14, 16, 18 ]
+        node: [ 12, 14, 16 ]
     name: Node ${{ matrix.node }} Test
     steps:
       - name: Checkout code

Diff for: README.md

@@ -2,7 +2,9 @@
 
 W3C XML Encryption implementation for node.js (http://www.w3.org/TR/xmlenc-core/)
 
-Supports node >= 12
+Supports node >= 12 < 18
+
+node 18 not supported due to https://github.com/nodejs/node/issues/52017 for Triple DES algorithms.
 
 ## Usage
 

Diff for: package.json

@@ -32,6 +32,6 @@
     "test": "mocha"
   },
   "engines": {
-    "node": ">=12"
+    "node": ">=12 < 18"
   }
 }