fix failing test

Author: StephenSmith25

pythonfmu3/_version.py

@@ -1 +1 @@
-__version__ = "0.3.0"
+__version__ = "0.3.1"

pythonfmu3/tests/test_fmi3slave.py

@@ -155,6 +155,10 @@ def do_step(self, t, dt):
 def test_Fmi3Slave_model_exchange():
     class Slave(Fmi3Slave, ModelExchange):
 
+        def __init__(self, **kwargs):
+            super().__init__(**kwargs)
+            self.time = 0.0
+
         def get_continuous_state_derivatives(self, vals):
             return []