Revert "chore: Remove the obsolete version property in docker-compose…

….yaml."

This reverts commit 9d59faa.

docker-compose.e2e.mysql.yaml

@@ -1,4 +1,4 @@
----
+version: "3"
 services:
   sync-db:
   tokenserver-db:

docker-compose.e2e.spanner.yaml

@@ -1,4 +1,4 @@
----
+version: "3"
 services:
   sync-db:
   sync-db-setup:

docker-compose.mysql.yaml

@@ -1,4 +1,3 @@
----
 # NOTE: This docker-compose file was constructed to create a base for
 # use by the End-to-end tests. It has not been fully tested for use in
 # constructing a true, stand-alone sync server.
@@ -9,6 +8,7 @@
 # you can test if it's available with
 # curl "http://localhost:8000/__heartbeat__"
 
+version: "3"
 services:
   sync-db:
     image: docker.io/library/mysql:5.7

docker-compose.spanner.yaml

@@ -1,4 +1,4 @@
----
+version: "3"
 services:
   sync-db:
     # Getting sporadic errors in spanner.