Fix error in test-deployment-pip (typedb#187)

## What is the goal of this PR?

There was an error in test-deployment-pip caused by old syntax, which we fixed.

## What are the changes implemented in this PR?

Fix error in test-deployment-pip

Author: Alex Walker

tests/deployment/test.py

@@ -47,7 +47,7 @@ def setUp(self):
     def test_database(self):
         dbs = client.databases().all()
         if "grakn" in dbs:
-            client.databases().delete("grakn")
+            client.databases().get("grakn").delete()
         client.databases().create("grakn")
         dbs = client.databases().all()
         self.assertTrue("grakn" in dbs)