support/testing: add python-cloudpickle tests

Add a basic runtime test for the python-cloudpickle package.
This test verifies the fundamental serialization capabilities of the
library by:
- Importing `cloudpickle`.
- Defining a simple Python function (fibonacci).
- Using `cloudpickle.dumps()` to serialize this function.

Signed-off-by: Xukai Wang <kingxukai@zohomail.com>
[Julien: fix flake8 warnings to fix check-package errors]
Signed-off-by: Julien Olivain <ju.o@free.fr>

support/testing/tests/package/sample_python_cloudpickle.py

@@ -0,0 +1,8 @@
+import cloudpickle
+
+
+def fibonacci(n):
+    return n if n < 2 else fibonacci(n-1) + fibonacci(n-2)
+
+
+serialized = cloudpickle.dumps(fibonacci)