fix: Replace deprecated assertEquals with assertEqual (#30241)

Replace deprecated assertEquals with assertEqual.

tests/test_modeling_flax_common.py

@@ -792,7 +792,7 @@ class FlaxModelTesterMixin:
             types = flatten_dict(types)
 
             for name, type_ in types.items():
-                self.assertEquals(type_, jnp.float32, msg=f"param {name} is not initialized in fp32.")
+                self.assertEqual(type_, jnp.float32, msg=f"param {name} is not initialized in fp32.")
 
     def test_to_bf16(self):
         config, _ = self.model_tester.prepare_config_and_inputs_for_common()