newer pyarrow as well

Author: isabelizimm

extensions/positron-python/python_files/positron/pinned-test-requirements.txt

@@ -18,7 +18,7 @@ pandas==2.0.3; python_version < '3.9'
 plotly==5.24.1
 polars==1.7.1
 polars[timezone]==1.7.1; python_version < '3.9' or sys_platform == 'win32'
-pyarrow==17.0.0
+pyarrow==18.1.0
 pytest==8.0.2
 pytest-asyncio==0.23.8
 pytest-mock==3.14.0