[Bugfix] GPTBigCodeForCausalLM: Remove lm_head from supported_lora_modules. (#6326)

Signed-off-by: Thomas Parnell <tpa@zurich.ibm.com>
Co-authored-by: Travis Johnson <tsjohnso@us.ibm.com>

vllm/model_executor/models/gpt_bigcode.py

@@ -235,7 +235,7 @@ class GPTBigCodeModel(nn.Module):
 class GPTBigCodeForCausalLM(nn.Module, SupportsLoRA):
     packed_modules_mapping = {"c_attn": ["c_attn"]}
 
-    supported_lora_modules = ["c_fc", "c_proj", "wte", "lm_head", "c_attn"]
+    supported_lora_modules = ["c_fc", "c_proj", "wte", "c_attn"]
 
     embedding_modules = {
         "wte": "input_embeddings",