arrow-odbc: only install a pyarrow wheel in the test env

pyarrow 26.0.0 is out on PyPI as an sdist only for riscv64, and
pypi.riseproject.dev's newest riscv64 wheel is 25.0.1. arrow-odbc's
`pyarrow>=8.0.0` lets pip pick the 26.0.0 sdist, whose build fails
("Could not find a package configuration file provided by Arrow"),
so installing the freshly built wheel failed for both 10.5.0 and
10.6.0 before any test ran. Restrict pyarrow to binary wheels so it
resolves to the riscv64 wheel instead.

Author: luhenry

.github/workflows/build-arrow-odbc.yml

@@ -180,6 +180,11 @@ jobs:
             --wheel-dir {dest_dir}
             {wheel}
           CIBW_TEST_REQUIRES: pytest
+          # arrow-odbc only asks for `pyarrow>=8.0.0`, so without this pip
+          # takes PyPI's newest pyarrow sdist (which has no riscv64 wheel and
+          # can't find an Arrow C++ install to build against) over the latest
+          # riscv64 wheel on pypi.riseproject.dev.
+          CIBW_TEST_ENVIRONMENT: PIP_ONLY_BINARY=pyarrow
           CIBW_TEST_SOURCES: tests
           CIBW_TEST_COMMAND: python -m pytest -v tests/test_riscv64_smoke.py