fix: jsr API for cloudflare worker env

Without this header will get html format instead of json in cf worker

packages/package-registry/src/jsr/index.ts

@@ -119,7 +119,11 @@ export function getJsrPackageSrcFile(
 	file: string
 ): Promise<string | undefined> {
 	const url = `https://jsr.io/@${scope}/${name}/${version}/${file}`
-	return fetch(url).then((res) => res.text())
+	return fetch(url, {
+		headers: {
+			Accept: "application/json"
+		}
+	}).then((res) => res.text())
 }
 
 /**