Fix gsm8k HF repo (#986)

Author: amstu2

src/lighteval/tasks/default_tasks.py

@@ -8590,7 +8590,7 @@
     name="gsm8k",
     suite=["lighteval"],
     prompt_function=prompt.gsm8k,
-    hf_repo="lighteval/openai/gsm8k",
+    hf_repo="openai/gsm8k",
     hf_subset="main",
     hf_avail_splits=["train", "test"],
     evaluation_splits=["test"],