Release sync for 20.08

- Classic charms: sync charm-helpers.
- Classic ceph based charms:  also sync charms.ceph
- Reactive charms: trigger a rebuild
- sync tox.ini
- sync requirements.txt and test-requirements.txt

Change-Id: Ie1f68f07abe763195de55f0e2f86e481b125d837

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
-91cb0fdc-a4d0-11ea-b69f-6f63bb868762
+d9db618c-d02c-11ea-8870-cf4b22eeb82f

test-requirements.txt

@@ -4,7 +4,7 @@
 #     https://github.com/openstack-charmers/release-tools
 #
 # Lint and unit test requirements
-flake8>=2.2.4
+flake8>=2.2.4,<=2.4.1
 stestr>=2.2.0
 requests>=2.18.4
 charms.reactive

tox.ini

@@ -50,6 +50,11 @@ basepython = python3.7
 deps = -r{toxinidir}/test-requirements.txt
 commands = stestr run --slowest {posargs}
 
+[testenv:py38]
+basepython = python3.8
+deps = -r{toxinidir}/test-requirements.txt
+commands = stestr run --slowest {posargs}
+
 [testenv:pep8]
 basepython = python3
 deps = -r{toxinidir}/test-requirements.txt