support/testing: drop docstring in TestPythonPackageBase::test_run()

support/testing: drop docstring in TestPythonPackageBase::test_run()

Having a docstring in the test_run() method clutters the "run-tests
-l" output:

test_run (tests.package.test_python_crossbar.TestPythonPy3Crossbar)
Test a python package. ... ok
[...]
test_run (tests.package.test_python_pexpect.TestPythonPy2Pexpect)
Test a python package. ... ok
test_run (tests.package.test_python_pexpect.TestPythonPy3Pexpect)
Test a python package. ... ok
test_run (tests.package.test_python_twisted.TestPythonPy2Twisted)
Test a python package. ... ok
test_run (tests.package.test_python_twisted.TestPythonPy3Twisted)
Test a python package. ... ok
test_run (tests.package.test_python_pynacl.TestPythonPy2Pynacl)
Test a python package. ... ok
test_run (tests.package.test_python_pynacl.TestPythonPy3Pynacl)
Test a python package. ... ok

So let's simply drop this docstring that is not particularly useful.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>