fix: Limit to node 16/17/18 as some dependencies do not work on node19 yet

The dependency tree-sitter does not yet compile for node 19 due to using a function which has been removed from v8 -- tree-sitter has a patch to get working on node 19 but it isn’t ready yet — tree-sitter/node-tree-sitter#113

in the interim, let's mark node 19 as not supported

Author: JakeChampion

package.json

@@ -2,7 +2,7 @@
   "name": "@fastly/js-compute",
   "version": "0.6.0",
   "engines": {
-    "node": "16 - 19",
+    "node": "16 - 18",
     "npm": "^8"
   },
   "license": "Apache-2.0",