Add a new get_held_count() API to get a count of held messages.

See merge request !122

This should be faster than actually getting those held messages and speed up
some pages in Postorius.

Add the new get_requests and get_requests_count API.

See merge request !121

This adds two new APIs, `get_requests()` and `get_requests_count()`. It wasn't
possible to extend ``requests`` since it is defined as a property and it isn't
possible to do the filtering with ``token_owner`` in that API.

Prepare for a 3.3.1rc1 release.

See merge request !120

Get a non-member by address.

See merge request !119

Remove upstream test until we figure out dependency testing properly.

See merge request !114

Use the MailingList's roster/nonmember API to get list of nonmembers

See merge request !117

For consistency purpose, use the roster API instead of the find API to get a
list of MailingList. This API isn't documented well, so previously we ended up
using the find API.

Add advertised flag to the MailingList object.

See merge request !115

- Bump test dependency on Mailman Core to 3.3.1rc1
- Remove some __future__ imports
- Remove vcr markers
- Fix tests for new version of Mailman Core.

Copyright year bump

See merge request !116

Fix tests for Mailmanclient.

See merge request !118

Fix a bug when the display_name of a Member is set to "None".

Closes #52

See merge request !113

Fixes #52

Fix the CI

See merge request !112

- Add logging for Mailman's Core runner
- Remove pytest-vcr and commands for it.
- In the MailmanConnectionError also include the error message
- Pin to importlib_resources < 0.2 for the API bug.
- Remove tox job for vcr record.

Add Python 3.8 and flake8-bugbear for linting tests.

Closes #49

See merge request !110

Allow specifying a reason when rejecting held messages.

Closes #49

See merge request !109

Closes #49

Version bump post release.

See merge request !108

Prepare for 3.3.0 release.

See merge request !107

Add support for tag and finding HeaderMatches for a list.

See merge request !105

Add support to set preferred address of a User.

See merge request !99

Version bump post release.

See merge request !104

Another alpha release due to change is error message format.

See merge request !103

Decode json response correctly to set exception message.

See merge request !102