Merge ~jneo8/charm-infra-node:build/juju-3.1 into charm-infra-node:master

[JamesLin]

build(juju-3.1): Un-pin juju version

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

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

[Eric Chen (eric-chen)]

wait for juju3.1 jenkins result

review: Approve

[Tianqi Xiao (txiao)]

Code change LGTM. Also waiting for +1 from CI

review: Approve

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

FAILED: Continuous integration, rev:6d600c488feb5d1f1823aa57a75e87f099872316
https://jenkins.canonical.com/bootstack/job/lp-charm-infra-node-ci/8/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/bootstack/job/lp-charm-test-functest/1907/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/571/

Click here to trigger a rebuild:
https://jenkins.canonical.com/bootstack/job/lp-charm-infra-node-ci/8//rebuild

review: Needs Fixing (continuous-integration)

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

PASSED: Continuous integration, rev:6d600c488feb5d1f1823aa57a75e87f099872316
https://jenkins.canonical.com/bootstack/job/lp-charm-infra-node-ci/9/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/bootstack/job/lp-charm-test-functest31/199/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/599/

Click here to trigger a rebuild:
https://jenkins.canonical.com/bootstack/job/lp-charm-infra-node-ci/9//rebuild

review: Approve (continuous-integration)

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

Change successfully merged at revision 7d9197388e6ff52d98f7192fdd05ccbf4d8286aa

diff --git a/src/tests/functional/requirements.txt b/src/tests/functional/requirements.txt
index 7c2fc7f..f76bfbb 100644
--- a/src/tests/functional/requirements.txt
+++ b/src/tests/functional/requirements.txt
@@ -1,5 +1,5 @@
 flake8
-juju<3  # https://bugs.launchpad.net/bugs/2007834
+juju
 mock
 pytest
 pytest-asyncio