Fix warnings by removing 'version' from all Docker Compose YAMLs

deployment/docker-compose.ocelotsocial-branded.yml

@@ -1,6 +1,4 @@
 # This docker-compose file is just here for testing
-version: "3.4"
-
 services:
 
   ########################################################

deployment/docker-compose.yml

@@ -1,6 +1,6 @@
 # This docker-compose file is just here for testing
-version: "3.4"
 services:
+
   webapp-base:
     image: ocelotsocialnetwork/webapp:local-base
     build: 

docker-compose.maintenance.yml

@@ -1,8 +1,7 @@
 # Todo: !!! This file seems related to our old maintenance worker for MongoDB and has to be refactored in case of using it !!!
 
-version: "3.4"
-
 services:
+
   maintenance-worker:
     image: ocelotsocialnetwork/develop-maintenance-worker:latest
     build:

docker-compose.override.yml

@@ -1,5 +1,3 @@
-version: "3.4"
-
 services:
 
   ########################################################

docker-compose.test.yml

@@ -1,5 +1,3 @@
-version: "3.4"
-
 services:
 
   ########################################################

docker-compose.yml

@@ -3,8 +3,6 @@
 # is required to explicitly define if you want an production build:
 # > docker-compose -f docker-compose.yml up 
 
-version: "3.4"
-
 services:
 
   ########################################################