Let reward model take text inputs instead of message lists (#1907)

Co-authored-by: Kyle Corbitt <kyle@corbt.com>

test/srt/models/test_embedding_models.py

@@ -30,6 +30,10 @@ TORCH_DTYPES = [torch.float16]
 
 class TestEmbeddingModels(unittest.TestCase):
 
+    @classmethod
+    def setUpClass(cls):
+        mp.set_start_method("spawn", force=True)
+
     def assert_close_prefill_logits(
         self,
         prompts,
@@ -74,9 +78,4 @@ class TestEmbeddingModels(unittest.TestCase):
 
 
 if __name__ == "__main__":
-    try:
-        mp.set_start_method("spawn")
-    except RuntimeError:
-        pass
-
     unittest.main()