drop support for node 16 too

.codesandbox/ci.json

@@ -1,5 +1,5 @@
 {
   "installCommand": "install:csb",
   "sandboxes": ["github/kentcdodds/react-testing-library-examples"],
-  "node": "16"
+  "node": "18"
 }

.github/workflows/validate.yml

@@ -29,7 +29,7 @@ jobs:
       # Otherwise we would not know if the problem is tied to the Node.js version
       fail-fast: false
       matrix:
-        node: [16, 18, 20]
+        node: [18, 20]
     runs-on: ubuntu-latest
     steps:
       - name: ⬇️ Checkout repo
@@ -78,7 +78,7 @@ jobs:
       - name: ⎔ Setup node
         uses: actions/setup-node@v3
         with:
-          node-version: 16
+          node-version: 18
 
       - name: 📥 Download deps
         uses: bahmutov/npm-install@v1

package.json

@@ -21,7 +21,7 @@
   "author": "Kent C. Dodds <me@kentcdodds.com> (https://kentcdodds.com)",
   "license": "MIT",
   "engines": {
-    "node": ">=16"
+    "node": ">=18"
   },
   "browserslist": [
     "and_chr 103",
@@ -40,7 +40,7 @@
     "safari 15.5",
     "samsung 17.0",
     "samsung 16.0",
-    "node 16.0"
+    "node 18.0"
   ],
   "scripts": {
     "build": "kcd-scripts build  --no-ts-defs --ignore \"**/__tests__/**,**/__node_tests__/**,**/__mocks__/**\" && kcd-scripts build --no-ts-defs --bundle --no-clean",