Fix build error related to trio dependency

Author: mehaase

requirements.txt

@@ -3,6 +3,6 @@ mock==2.0.0
 pytest-cov==2.6.1
 pytest==4.3.1
 six==1.12.0
-trio==0.11.0
-pytest-trio==0.5.2
-async-generator==1.10
+trio==0.11.0; python_version>="3.6"
+pytest-trio==0.5.2; python_version>="3.6"
+async-generator==1.10; python_version>="3.6"

tests/conftest.py

@@ -4,4 +4,6 @@
 if sys.version_info < (3, 4):
     collect_ignore += ["integration/test_asyncio.py", "integration/test_asyncio_coroutine.py"]
 elif sys.version_info < (3, 6):
-    collect_ignore.append("integration/test_asyncio.py")
+    collect_ignore.append("integration/test_asyncio.py")
+if sys.version_info < (3, 6):
+    collect_ignore.append("integration/test_trio.py")

tests/integration/test_trio.py

@@ -36,8 +36,6 @@ async def marvel_table(integration_db, nursery):
 
 @pytest.mark.trio
 @pytest.mark.integration
-@pytest.mark.skipif(sys.version_info < (3, 6),
-                    reason="Async generators require python ≥ 3.6")
 async def test_trio(marvel_table, nursery):
     """
     Test the flow for 3.6 and up, async generators are