Publish as ESM-only

Require Node v20.19 (which enables require(esm) support by default).

This new package is supposed to be compatible with Apollo Server 4 which
does an elaborate dance to publish as both CJS and ESM, but we already
decided it was OK for this package itself to require Node v20.

Turns out CJS-only plays poorly with the AS4-style dual build:
apollographql/apollo-server#8069

And we're likely to go ESM-only with AS5 because newer Node makes this
easier. So let's do that here too.

Author: glasser

.changeset/modern-kiwis-look.md

@@ -0,0 +1,5 @@
+---
+'@as-integrations/express5': major
+---
+
+Publish as ESM-only, and require Node v20.19 (which enables require(esm) support by default).

package-lock.json

@@ -12,10 +12,12 @@
   "bugs": {
     "url": "https://github.com/apollo-server-integrations/apollo-server-integration-express5/issues"
   },
-  "main": "dist/index.js",
-  "types": "dist/index.d.ts",
+  "type": "module",
+  "exports": {
+    ".": "./dist/index.js"
+  },
   "engines": {
-    "node": ">=20"
+    "node": ">=20.19"
   },
   "scripts": {
     "build": "tsc --build tsconfig.build.json",

package.json

@@ -2,9 +2,8 @@
   "compilerOptions": {
     "rootDir": "./src",
     "outDir": "./dist",
-    "target": "es2020",
-    "module": "commonjs",
-    "moduleResolution": "node",
+    "target": "ESNext",
+    "module": "NodeNext",
     "esModuleInterop": true,
     "sourceMap": true,
     "declaration": true,