Add pytest configuration. (sonic-net#24339)

Why I did it
Pytest in sonic-buildimage and submodules relies on default value of norecursedirs setting.
Without the configuration file, pytest may find another one in one of the parent directories and run with an incompatible setting of norecursedirs causing test collection failures.

How I did it
Create an empty pytest.ini configuration file.

Description for the changelog
Ensure pytest runs with default value of norecursedirs

Signed-off-by: Krzysztof Kościuszkiewicz <[email protected]>

Author: kkosciuszkiewicz-arista

pytest.ini

@@ -0,0 +1,5 @@
+# Configuration is deliberately left empty.
+# Presence of the file ensures pytest will select this directory as the rootdir.
+# Otherwise pytest may keep going up the directory tree and find another
+# configuration file.
+[pytest]