fixed tests for twisted change (#950)

* fixed tests for twisted change
diff --git a/tox.ini b/tox.ini
index 5fc6ebb..4217abb 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,11 +24,7 @@
 
 [testenv:py37-twistedMaster]
 deps =
-    # [tls,conch] syntax doesn't work here so we enumerate all dependencies.
-    git+https://github.com/twisted/twisted
-    idna
-    service_identity
-    bcrypt
+    Twisted[all_non_platform] @ git+https://github.com/twisted/twisted
 setenv =
 passenv = ARCHFLAGS CFLAGS LC_ALL LDFLAGS PATH LD_LIBRARY_PATH TERM
 commands =