Fix NameError: rename RequestRate to Rate and deprecate Python 3.8/3.9

[Copilot]

The import statement was changed to remove RequestRate, but line 35 still referenced it, causing a runtime NameError. Additionally, Python 3.8 and 3.9 support has been deprecated, with the minimum Python version now set to 3.10.

Changes:

• Added Rate to imports from pyrate_limiter
• Updated arxiv adapter to use Rate instead of RequestRate
• Removed Python 3.8 and 3.9 from package classifiers in pyproject.toml
• Updated requires-python to >=3.10 in pyproject.toml
• Updated GitHub Actions test workflow to test with Python 3.10 and 3.13
• Updated README.md to reflect minimum Python version requirement of 3.10

# Before (broken)
from pyrate_limiter import Duration, Limiter
adapter_arxiv = LimiterAdapter(
    limiter=Limiter(RequestRate(1, Duration.SECOND * 3)), ...  # NameError
)

# After
from pyrate_limiter import Duration, Limiter, Rate
adapter_arxiv = LimiterAdapter(
    limiter=Limiter(Rate(1, Duration.SECOND * 3)), ...
)

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[Copilot]

Pull request overview

This WIP pull request updates the import and usage of RequestRate to Rate from the pyrate_limiter library, reflecting an API change in the library. The change only affects the rate limiting configuration for the arXiv API adapter.

Changes:

• Updated import statement to use Rate instead of RequestRate from pyrate_limiter
• Updated the arXiv adapter configuration to use Rate instead of RequestRate

---

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[njzjz]

@copilot Deprecate Python 3.8 and 3.9. The minimal Python version is now 3.10.

[Copilot]

@copilot Deprecate Python 3.8 and 3.9. The minimal Python version is now 3.10.

Done! I've deprecated Python 3.8 and 3.9. The minimal Python version is now 3.10. Updated pyproject.toml classifiers, requires-python field, GitHub Actions test workflow, and README.md. (commit dc0adb2)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.10%. Comparing base (71ec7a6) to head (dc0adb2).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #89      +/-   ##
==========================================
- Coverage   87.58%   87.10%   -0.49%     
==========================================
  Files          13       12       -1     
  Lines         580      504      -76     
==========================================
- Hits          508      439      -69     
+ Misses         72       65       -7     

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