ansible-test - Fix `pylint` error.

This prevents `pylint` from failing with warnings reported as errors and with no test results given.

Resolves https://github.com/ansible/ansible/issues/75791

changelogs/fragments/ansible-test-isort.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - ansible-test - Update ``isort`` constraint from version 4.3.15 to 4.3.16 to prevent ``pylint`` from failing with warnings reported as errors.

test/lib/ansible_test/_data/requirements/constraints.txt

@@ -49,7 +49,7 @@ MarkupSafe < 2.0.0 ; python_version < '3.6' # MarkupSafe >= 2.0.0. requires Pyth
 
 # freeze pylint and its requirements for consistent test results
 astroid == 2.3.3
-isort == 4.3.15
+isort == 4.3.16
 lazy-object-proxy == 1.4.3
 mccabe == 0.6.1
 pylint == 2.3.1