Merge ~martin-kalcok/juju-lint:pin-libjuju into juju-lint:master

[Martin Kalcok]

Pin "juju" library to maintain compatibility with Juju <3.0

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

FAILED: Continuous integration, rev:ccd4dbf6c3263dee2340e6b4a6f368eae7195760
https://jenkins.canonical.com/bootstack/job/lp-juju-lint-ci/3/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/bootstack/job/lp-charm-test-functest/389/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/149/

Click here to trigger a rebuild:
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review: Needs Fixing (continuous-integration)

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

PASSED: Continuous integration, rev:97a468eacc3c3fc7d8f5b4bef3af12ea4fb81b7f
https://jenkins.canonical.com/bootstack/job/lp-juju-lint-ci/4/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/bootstack/job/lp-charm-test-functest/390/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/150/

Click here to trigger a rebuild:
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review: Approve (continuous-integration)

[Gabriel Cocenza (gabrielcocenza)]

LGTM

review: Approve

[Ramesh Sattaru (rameshcan)]

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision edfb5d19b1bac5c2f3a87b5c8ec7660c65307552

diff --git a/tests/functional/requirements.txt b/tests/functional/requirements.txt
index 6a1cad4..eab92d5 100644
--- a/tests/functional/requirements.txt
+++ b/tests/functional/requirements.txt
@@ -1,3 +1,5 @@
 pytest
 pytest-operator
 pytest-httpserver
+# pin juju library to maintain compatibility with Juju controller < 3.0
+juju < 3.0