Connection singleton (#265)

Created a Singleton for the connection classes.

acceptance/python/src/test_zenroom.py

@@ -38,6 +38,34 @@ def test_zenroom_signing(
     zenroomscpt = ZenroomSha256(script=fulfill_script_zencode, data=zenroom_data, keys=zen_public_keys)
     print(f"zenroom is: {zenroomscpt.script}")
 
+
+def test_zenroom_signing(
+    gen_key_zencode,
+    secret_key_to_private_key_zencode,
+    fulfill_script_zencode,
+    zenroom_data,
+    zenroom_house_assets,
+    condition_script_zencode,
+):
+
+    biolabs = generate_keypair()
+    version = "2.0"
+
+    alice = json.loads(zencode_exec(gen_key_zencode).output)["keyring"]
+    bob = json.loads(zencode_exec(gen_key_zencode).output)["keyring"]
+
+    zen_public_keys = json.loads(
+        zencode_exec(secret_key_to_private_key_zencode.format("Alice"), keys=json.dumps({"keyring": alice})).output
+    )
+    zen_public_keys.update(
+        json.loads(
+            zencode_exec(secret_key_to_private_key_zencode.format("Bob"), keys=json.dumps({"keyring": bob})).output
+        )
+    )
+
+    zenroomscpt = ZenroomSha256(script=fulfill_script_zencode, data=zenroom_data, keys=zen_public_keys)
+    print(f"zenroom is: {zenroomscpt.script}")
+
     # CRYPTO-CONDITIONS: generate the condition uri
     condition_uri_zen = zenroomscpt.condition.serialize_uri()
     print(f"\nzenroom condition URI: {condition_uri_zen}")
@@ -73,6 +101,7 @@ def test_zenroom_signing(
         "output": ["ok"],
         "policies": {},
     }
+    metadata = {"result": {"output": ["ok"]}}
 
     token_creation_tx = {
         "operation": "CREATE",