AC: Set the pytest JUnit report format to 2

Roman Donchenko · Roman Donchenko · commit 416830730a3e · 2020-02-11T19:36:54.000+03:00
It's going to be the default in pytest 6, and pytest 5 warns about this.
We should be OK with version 2, so let's update now.
diff --git a/tools/accuracy_checker/pytest.ini b/tools/accuracy_checker/pytest.ini
@@ -0,0 +1,2 @@
+[pytest]
+junit_family=xunit2
