add test_gates

tests/test_gates.py

@@ -0,0 +1,9 @@
+from qujax import gates
+from qujax.circuit_tools import check_unitary
+
+
+def test_gates():
+    for g_str, g in gates.__dict__.items():
+        if g_str[0] != '_' and g_str != 'jnp':
+            check_unitary(g_str)
+            check_unitary(g)