bump version to 4.8.0

Author: Anna Yan

Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v2
 name: retool
 description: A Helm chart for Kubernetes
 type: application
-version: 4.7.0
+version: 4.8.0
 maintainers:
   - name: Retool Engineering
     email: engineering+helm@retool.com