fix test TestCrossCodebookComputations::test_precomp

Summary: To fix the nightly: https://app.circleci.com/pipelines/github/facebookresearch/faiss/4815/workflows/2027a135-72ee-459f-a092-7ada95affd41/jobs/26225

Reviewed By: mdouze

Differential Revision: D50839933

fbshipit-source-id: 311b548182a2b3966c9603f83c115fa038eb19e8

tests/test_residual_quantizer.py

@@ -1117,7 +1117,7 @@ def test_precomp(self):
             K = 1 << rq.nbits.at(m)
             cpp_table = codebook_cross_prods[ofs:ofs + K * kk].reshape(kk, K)
             ofs += kk * K
-            np.testing.assert_allclose(py_table, cpp_table, rtol=2e-4)
+            np.testing.assert_allclose(py_table, cpp_table, atol=1e-5)
 
         cent_norms = faiss.vector_to_array(rq.cent_norms)
         np.testing.assert_array_almost_equal(