Add .coveragerc with subprocess support (#1819)

SUMMARY:
Add a `.coveragerc` file to support the recent release of `pytest-cov`:

https://github.com/pytest-dev/pytest-cov/blob/224d8964caad90074a8cf6dc8720b8f70f31629b/CHANGELOG.rst#700-2025-09-09

This is required due to a change in `pytest-cov` v7.0.0 because of the
use of subprocesses (particularly with the examples tests).

TEST PLAN:
This run demonstrates that this change fixes the issue with code
coverage collection for the examples tests:
https://github.com/neuralmagic/llm-compressor-testing/actions/runs/17741780708

Signed-off-by: Domenic Barbuzzi <dbarbuzz@redhat.com>
Co-authored-by: Dipika Sikka <dipikasikka1@gmail.com>

Author: dbarbuzzi

.coveragerc

@@ -0,0 +1,2 @@
+[run]
+patch = subprocess