create separate functions for ISR routes (#9504)

Co-authored-by: Rich Harris <[email protected]>

Author: Rich-Harris

.changeset/early-pigs-boil.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+fix: create separate functions for ISR routes

packages/adapter-vercel/index.js

@@ -358,7 +358,8 @@ function hash_config(config) {
 		config.external ?? '',
 		config.regions ?? '',
 		config.memory ?? '',
-		config.maxDuration ?? ''
+		config.maxDuration ?? '',
+		!!config.isr // need to distinguish ISR from non-ISR functions, because ISR functions can't use streaming mode
 	].join('/');
 }