Add support for testing with Python 3.10.

.azure-pipelines/azure-pipelines.yml

@@ -69,6 +69,7 @@ stages:
             - test: 3.7
             - test: 3.8
             - test: 3.9
+            - test: '3.10'
   - stage: Windows
     dependsOn: []
     jobs:

changelogs/fragments/ansible-test-python-3.10.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - ansible-test - Add support for testing with Python 3.10.

test/lib/ansible_test/_data/completion/docker.txt

@@ -1,5 +1,5 @@
-default name=quay.io/ansible/default-test-container:3.4.0 python=3.9,2.6,2.7,3.5,3.6,3.7,3.8 seccomp=unconfined context=collection
+default name=quay.io/ansible/default-test-container:3.5.0 python=3.9,2.6,2.7,3.5,3.6,3.7,3.8,3.10 seccomp=unconfined context=collection
-default name=quay.io/ansible/ansible-core-test-container:3.4.0 python=3.9,2.6,2.7,3.5,3.6,3.7,3.8 seccomp=unconfined context=ansible-core
+default name=quay.io/ansible/ansible-core-test-container:3.5.1 python=3.9,2.6,2.7,3.5,3.6,3.7,3.8,3.10 seccomp=unconfined context=ansible-core
 alpine3 name=quay.io/ansible/alpine3-test-container:2.0.2 python=3.8
 centos6 name=quay.io/ansible/centos6-test-container:2.0.2 python=2.6 seccomp=unconfined
 centos7 name=quay.io/ansible/centos7-test-container:2.0.2 python=2.7 seccomp=unconfined

test/lib/ansible_test/_internal/util.py

@@ -123,6 +123,7 @@ SUPPORTED_PYTHON_VERSIONS = (
     '3.7',
     '3.8',
     '3.9',
+    '3.10',
 )