feat(node): drop support for node < 18, 19

BREAKING CHANGE: node versions < 18, 19 are no longer
supported.

Author: djcsdy

package.json

@@ -23,7 +23,7 @@
   },
   "sideEffects": false,
   "engines": {
-    "node": "^14 || ^16 || >=18"
+    "node": "^18 || >=20"
   },
   "dependencies": {
     "@softwareventures/nullable": "^1.0.0 || ^2.0.0 || ^3.0.0",