Merge ~dbungert/curtin:unittest-py310 into curtin:master

[Dan Bungert]

tox: drop xenial-py3 from default env list

Running xenial-era python packages against modern python is not likely
to be successful! If this is an interesting test then we should support
that all the way - with a matching python version and other
dependencies, or not at all.

[Michael Hudson-Doyle (mwhudson)]

review: Approve

[Michael Hudson-Doyle (mwhudson)]

Yeah we should run tests like this in a xenial container or something

[Server Team CI bot (server-team-bot)]

Autolanding: FAILED
More details in the following jenkins job:
https://jenkins.canonical.com/server-team/job/curtin-autoland-test/2/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/server-team/job/curtin-autoland-test/nodes=metal-amd64/2/
    ABORTED: https://jenkins.canonical.com/server-team/job/curtin-autoland-test/nodes=metal-ppc64el/2/
    ABORTED: https://jenkins.canonical.com/server-team/job/curtin-autoland-test/nodes=metal-s390x/2/

review: Needs Fixing (continuous-integration)

[Server Team CI bot (server-team-bot)]

Autolanding: FAILED
More details in the following jenkins job:
https://jenkins.canonical.com/server-team/job/curtin-autoland-test/3/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/server-team/job/curtin-autoland-test/nodes=metal-amd64/3/
    FAILURE: https://jenkins.canonical.com/server-team/job/curtin-autoland-test/nodes=metal-ppc64el/3/
    FAILURE: https://jenkins.canonical.com/server-team/job/curtin-autoland-test/nodes=metal-s390x/3/

review: Needs Fixing (continuous-integration)

[Server Team CI bot (server-team-bot)]

review: Approve (continuous-integration)

diff --git a/tox.ini b/tox.ini
index a169f19..2fc4027 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,8 +6,7 @@ envlist =
    py3,
    py3-pyflakes,
    py3-pylint,
-   block-schema,
-   xenial-py3
+   block-schema
 
 [tox:jenkins]
 downloadcache = ~/cache/pip