chore: update engines node version to 20

Author: angelcaamal

healthcare/consent/package.json

@@ -6,7 +6,7 @@
   "author": "Google LLC",
   "repository": "GoogleCloudPlatform/nodejs-docs-samples",
   "engines": {
-    "node": ">=12.0.0"
+    "node": ">=20.0.0"
   },
   "scripts": {
     "test": "c8 mocha -p -j 2 system-test/*.test.js --timeout=60000"

iam/deny/package.json

@@ -8,7 +8,7 @@
     "url": "https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git"
   },
   "engines": {
-    "node": ">=16.0.0"
+    "node": ">=20.0.0"
   },
   "scripts": {
     "test": "c8 mocha -p -j 2 test/*.test.js --timeout=60000"

media/video-stitcher/package.json

@@ -4,7 +4,7 @@
   "license": "Apache-2.0",
   "author": "Google LLC",
   "engines": {
-    "node": ">=10"
+    "node": ">=20.0.0"
   },
   "files": [
     "*.js"