Typo to get fourth parameter for setupPostgres.sh

Currently the CHART_NAME is either the value of the variable if defined, otherwise '4'.
It would be better to be the fourth parameter of the script if not defined.

stable/jfrog-platform/files/setupPostgres.sh

@@ -104,7 +104,7 @@ setupDB(){
 : ${DB_NAME:=$1}
 : ${DB_USERNAME:=$2}
 : ${DB_PASSWORD:=$3}
-: ${CHART_NAME:=4}
+: ${CHART_NAME:=$4}
 
 ### Following are the postgres details being setup for each service.
 ##  Common details
@@ -124,4 +124,4 @@ setupDB "${DB_USERNAME}" "${DB_PASSWORD}" "${DB_NAME}" || true
 
 log "$POSTGRES_LABEL setup is now complete."
 
-exit 0
+exit 0