support/testing: test_python_txaio: include twisted sample

Prior to b7d251293a20, txaio would test both asyncio and twisted.

Add back the twisted sample and include the twisted package in the
config so both modes of the package are tested.

Fixes: b7d251293a20 ("package/python-txaio: drop python 2 support")
Signed-off-by: Vincent Fazio <vfazio@xes-inc.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>
(cherry picked from commit 41b08a779b46082f20a1bd54b1a6af47a52a421c)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/testing/tests/package/test_python_txaio.py

@@ -7,5 +7,6 @@ class TestPythonPy3Txaio(TestPythonPackageBase):
         """
         BR2_PACKAGE_PYTHON3=y
         BR2_PACKAGE_PYTHON_TXAIO=y
+        BR2_PACKAGE_PYTHON_TWISTED=y
         """
-    sample_scripts = ["tests/package/sample_python_txaio_asyncio.py"]
+    sample_scripts = ["tests/package/sample_python_txaio_asyncio.py", "tests/package/sample_python_txaio_twisted.py"]