ci: update feature template label to pending triage (#19553)

Author: btea

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -1,6 +1,6 @@
 name: "\U0001F680 New feature proposal"
 description: Propose a new feature to be added to Vite
-labels: ["enhancement: pending triage"]
+labels: ["pending triage"]
 type: Feature
 body:
   - type: markdown