I got it to work! CBLAS is not being included with find_package(BLAS REQUIRED) in the basix/cpp/CMakeLists.txt file.
To fix that, I found my answer here: I added
set(BLAS_LIBRARIES "-lcblas;-lblas")
above target_link_libraries(basix PRIVATE ${BLAS_LIBRARIES})
After installing the package, I renamed basix/test/test_numba.py, and all tests passed.