feat(firebase): upgrade default runtime to node 20

docs/2.deploy/20.providers/firebase.md

@@ -193,7 +193,7 @@ You can set custom Node.js version in configuration:
 ```ts [nitro.config.ts]
 export default defineNitroConfig({
   firebase: {
-    nodeVersion: "18" // Can be "16", "18", "20" or "22"
+    nodeVersion: "20" // Can be "16", "18", "20" or "22"
   },
 });
 ```
@@ -202,7 +202,7 @@ export default defineNitroConfig({
 export default defineNuxtConfig({
   nitro: {
     firebase: {
-      nodeVersion: "18" // Can be "16", "18", "20" or "22"
+      nodeVersion: "20" // Can be "16", "18", "20" or "22"
     },
   },
 });
@@ -218,7 +218,7 @@ You might also need to add a runtime key to your `firebase.json` file:
 {
   "functions": {
     "source": ".output/server",
-    "runtime": "nodejs18"
+    "runtime": "nodejs20"
   }
 }
 ```

src/presets/firebase/utils.ts

@@ -48,8 +48,7 @@ export async function updatePackageJSON(nitro: Nitro) {
     ),
     engines: {
       // https://cloud.google.com/functions/docs/concepts/nodejs-runtime
-      // const supportedNodeVersions = new Set(["20", "18", "16"]);
-      node: nitro.options.firebase?.nodeVersion || "18",
+      node: nitro.options.firebase?.nodeVersion || "20",
     },
   });
 }