add feature multithreading for create trade with Dask distributed

freqtrade/tests/test_multithreading.py

@@ -0,0 +1,11 @@
+from freqtrade import (multithreading)
+
+
+def test_client_init():
+    # Check if create a Dask Client
+    default_conf = {}
+    default_conf.update({
+        'multithreading': {'use_multithreading': True, 'workers_number': 4}
+    })
+    client = multithreading.init(default_conf)
+    assert (str(type(client))) == "<class 'distributed.client.Client'>"