Update Nextcloud container name.

For some reason, Docker Compose changed from underscore to hyphen.

app.py

@@ -12,7 +12,7 @@ client = docker.from_env()
 
 
 NAME = os.getenv("NC_NAME", "Nimrod Adar")
-CONTAINER_NAME = os.getenv("NC_CONTAINER", "nextcloud_nextcloud_1")
+CONTAINER_NAME = os.getenv("NC_CONTAINER", "nextcloud-nextcloud-1")
 
 
 @app.route("/ping")