Ensure get_requests_for_local_unit doesn't fail on incomplete relation

This is a rebuild/make sync for charms to pickup the fix in charmhelpers to fix
any inadvertant accesses of ['ca'] in the relation data before it is available
from vault in the certificates relation.  Fix in charmhelpers is in [1].

[1] juju/charm-helpers#824
Closes-Bug: #2028683

Change-Id: I8dbac80c0e714c8b639bdd0df1b64a7026894938

rebuild

@@ -2,4 +2,4 @@
 # when dependencies of the charm change,
 # but nothing in the charm needs to.
 # simply change the uuid to something new
-53cf1d5c-1178-11ec-8ac2-bb3a2551099e
+082522d2-31fd-11ee-8ec3-b3fe23166eee