Update tests due to the deprecated qml.sample usage when `shots=Non…

…e` (#132)

* fix test_apply.py errors where the number of shots was not set explicitly

* get PL master temporarily

* Update requirements.txt

tests/test_apply.py

@@ -562,6 +562,7 @@ def test_sample_values(self, qubit_device_2_wires, tol):
         # initialized during reset
         qubit_device_2_wires.reset()
 
+        qubit_device_2_wires.shots = 1000
         qubit_device_2_wires.apply([qml.RX(1.5708, wires=[0])])
         qubit_device_2_wires._wires_measured = {0}
         qubit_device_2_wires._samples = qubit_device_2_wires.generate_samples()
@@ -996,6 +997,7 @@ def test_multi_samples_return_correlated_results(self, qubit_device_2_wires):
         """
 
         dev = qubit_device_2_wires
+        dev.shots = 1000
 
         @qml.qnode(dev)
         def circuit():
@@ -1015,7 +1017,7 @@ def test_multi_samples_return_correlated_results_more_wires_than_size_of_observa
         the correct dimensions
         """
 
-        dev = qml.device("lightning.qubit", wires=num_wires)
+        dev = qml.device("lightning.qubit", wires=num_wires, shots=1000)
 
         @qml.qnode(dev)
         def circuit():
@@ -1237,7 +1239,7 @@ def test_pauliz_hadamard(
         )
 
         dev._wires_measured = {0, 1, 2}
-        dev._samples = dev.generate_samples() if shots is not None else None
+        dev._samples = dev.generate_samples() if dev.shots is not None else None
 
         s1 = obs.eigvals
         p = dev.marginal_prob(dev.probability(), wires=obs.wires)