upgrade metallb to 6.4.20

Author: sophiebsw

apps/versions.toml

@@ -58,7 +58,7 @@ version = "v1.6.0"
 github = "https://github.com/kubevirt/kubevirt"
 
 [metallb]
-version = "6.1.2"
+version = "6.4.20"
 helm = "https://charts.bitnami.com/bitnami"
 
 [metrics-server]