removed version line from docker compose yaml (#800)

Co-authored-by: andrew <110792083+beboprocky@users.noreply.github.com>

docker-compose.yml

@@ -1,5 +1,3 @@
-version: '3'
-
 services:
   linkding:
     container_name: "${LD_CONTAINER_NAME:-linkding}"
@@ -10,4 +8,4 @@ services:
       - "${LD_HOST_DATA_DIR:-./data}:/etc/linkding/data"
     env_file:
       - .env
-    restart: unless-stopped
+    restart: unless-stopped