use mysql 8.0v for fedora/rockylinux

charts/oai-5g-core/mysql/values.yaml

@@ -2,7 +2,8 @@
 ## ref: https://hub.docker.com/r/library/mysql/tags/
 ##
 image: "docker.io/mysql"
-imageTag: "5.7"
+imageTag: "8.0" # this version works well for Fedora and Rocky Linux
+#imageTag: "5.7" # this version works well for ubuntu only
 
 replicas: 1