[charm lib] Update dependency ops to v2.9.0 (#304)

* [charm lib] Update dependency ops to v2.9.0

* Update agent

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Dragomir Penev <[email protected]>

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -54,7 +54,7 @@ jobs:
         juju:
           - agent: 2.9.45
             libjuju: ^2
-          - agent: 3.1.6
+          - agent: 3.1.7
     name: Integration test charm | ${{ matrix.juju.agent }}
     needs:
       - lint