Require datasets 4.1.0 (#650)

## Summary

Update Huggingface datasets dependency: unversioned dependency can break
with an old previously installed datasets package.

## Details

We previously had an unversioned dependency on datasets, and a recent
report shows that GuideLLM is not compatible with versions of datasets
prior to 3.1.0.

Since the "audio" extra already depends on datasets 4.1.0 we know that
works and it seems a reasonable target.

## Test Plan



## Related Issues


---

- [x] "I certify that all code in this PR is my own, except as noted
below."

## Use of AI

- [ ] Includes AI-assisted code completion
- [ ] Includes code generated by an AI application
- [ ] Includes AI-generated tests (NOTE: AI written tests should have a
docstring that includes `## WRITTEN BY AI ##`)

Author: sjmonson

pyproject.toml

@@ -52,7 +52,7 @@ keywords = [
 dependencies = [
     "click~=8.3.0",
     "culsans~=0.10.0",
-    "datasets",
+    "datasets>=4.1.0",
     "eval_type_backport",
     "faker",
     "ftfy>=6.0.0",