fix copy/pasta typos wikipedia->arxiv (#3222)

just updates a few module level docstrings from Wikipedia -> Arxiv

langchain/tools/arxiv/tool.py

@@ -1,4 +1,4 @@
-"""Tool for the Wikipedia API."""
+"""Tool for the Arxiv API."""
 
 from langchain.tools.base import BaseTool
 from langchain.utilities.arxiv import ArxivAPIWrapper

tests/integration_tests/test_arxiv.py

@@ -1,4 +1,4 @@
-"""Integration test for Wikipedia API Wrapper."""
+"""Integration test for Arxiv API Wrapper."""
 import pytest
 
 from langchain.utilities import ArxivAPIWrapper