update-balena-supervisor: add network-online dependency

There is a race condition present when purging a device and rebooting. If "update-balena-supervisor" comes up before the device can connect to the internet, it will fail to pull the supervisor image. As this service stops "balena-supervisor.service" , this isn't attempted again for at least 15 min = (up to 1 hour) when the "update-balena-supervisor.timer" triggers it.

Change-type: patch
Signed-off-by: Ryan Cooke <ryan@balena.io>

meta-balena-common/recipes-containers/balena-supervisor/balena-supervisor/update-balena-supervisor.service

@@ -3,7 +3,8 @@ Description=Balena supervisor updater
 Requires=\
     balena.service \
     bind-etc-balena-supervisor.service \
-    tmp.mount
+    tmp.mount \
+    network-online.target
 Wants=\
     mnt-boot.mount \
     balena-supervisor.service
@@ -12,7 +13,8 @@ After=\
     tmp.mount \
     mnt-boot.mount \
     bind-etc-balena-supervisor.service \
-    balena-supervisor.service
+    balena-supervisor.service \
+    network-online.target
 
 [Service]
 Type=simple