updated adtran_onu test requirements

Change-Id: Ibec5c7c54593716b68d74a5daad6a9c3cfdf96a4
diff --git a/voltha/adapters/adtran_onu/test_requirements.txt b/voltha/adapters/adtran_onu/test_requirements.txt
index 4d8a401..00910af 100644
--- a/voltha/adapters/adtran_onu/test_requirements.txt
+++ b/voltha/adapters/adtran_onu/test_requirements.txt
@@ -1,4 +1,5 @@
 -r ../../../requirements.txt
-pytest >= 3.0, < 4.0
-pytest-cov >= 2.1.0, < 3.0
-pytest-profiling >= 1.1.1, < 2.0
+pytest
+pytest-cov
+pytest-profiling
+pytest-twisted