Fix Falcon weight mapping for H2O.ai checkpoints

During the safetensor conversion, duplicate weights are removed.
However, which of the duplicates gets removed, differs per checkpoint.
In some, like `h2oai/h2ogpt-oig-oasst1-falcon-40b`, the weight
`transformer.word_embeddings.weightSafetensor` gets removed. In others,
`lm_head.weight` gets removed. Long story long, we need to support both.

Originally, f018143 mapped `lm_head` to `word_embeddings`. Then ac736fd
switched this around. This commit merges them and allows for both.

server/text_generation_server/models/flash_rw.py

@@ -54,7 +54,10 @@ class FlashRWSharded(FlashCausalLM):
             device,
             dtype,
             process_group=self.process_group,
-            aliases={"lm_head.weight": ["transformer.word_embeddings.weight"]},
+            aliases={
+                "lm_head.weight": ["transformer.word_embeddings.weight"],
+                "transformer.word_embeddings.weight": ["lm_head.weight"],
+            },
         )
 
         config.quantize = quantize