Remove several errant trailing empty lines

geonetwork/stack.yml

@@ -20,4 +20,3 @@ services:
 
 volumes:
     geonetwork:
-

mariadb/stack.yml

@@ -14,4 +14,3 @@ services:
         restart: always
         ports:
             - 8080:8080
-

mysql/stack.yml

@@ -14,4 +14,3 @@ services:
         restart: always
         ports:
             - 8080:8080
-

percona/stack.yml

@@ -14,4 +14,3 @@ services:
         restart: always
         ports:
             - 8080:8080
-