Bad usability when running software tests the first time

[amotl]

Problem

When running the test suite, tests/test_kinesis.py::test_kinesis_stream_operations seems to stall forever, while it is just downloading the LocalStack OCI image, which certainly takes some time, especially on a slow internet connection.

Proposal

Having a good informational message emitted by pytest before invoking the (implicit) docker pull operation will certainly be nice, in order to inform users better about what's currently going on, and that the duration of the next step will depend on the speed of the internet connection.