Feature 10509 manual scaling for native k8s charm

Juju version has to be upgraded to 2.8.6 because of a typo error.
You can see bug report: https://github.com/juju/python-libjuju/issues/477
and release note: https://github.com/juju/python-libjuju/commit/facd1f19eae65728b6c7c3b823939bb35ae45ed2



Change-Id: Iae4262e64debdf6b4d36b37778ec29f0dd46bac1
Signed-off-by: aktas <emin.aktas@ulakhaberlesme.com.tr>