Add pytest/pytest-cov support for pre-commit

Pytest (testing framework) and pytest-cov are now part of the python
environment and run automatically by pre-commit hook.

Change-Id: If55cae9f29391c80c809a0487785786a7b9ae62a
Signed-off-by: Diego Russo <diego.russo@arm.com>
diff --git a/.gitignore b/.gitignore
index 7512fe2..5081960 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 .eggs/
 build/
 ethos_u_vela.egg-info/
-ethosu/*.so
\ No newline at end of file
+ethosu/*.so
+.coverage
\ No newline at end of file