fix binomial sample test on TPU

The recent partitionable Threefry upgrade affects binomial sampling under the RBG PRNG scheme because the implementation of `jax.random.binomial` derives internal subkeys with a call to `split`. This led a randomized test to fail by pushing its numeric closeness check just beyond its current relative tolerance. This is very likely a false failure, so we update the rtol.

PiperOrigin-RevId: 723100174

Author: froystig

tests/random_lax_test.py

@@ -1219,7 +1219,7 @@ def testBinomialSample(self, n, p, dtype):
     for samples in [uncompiled_samples, compiled_samples]:
       self._CheckChiSquared(samples.astype(int), pmf, pval=1e-3)
       self.assertAllClose(samples.mean(), n * p, rtol=0.025, check_dtypes=False)
-      self.assertAllClose(samples.var(), n * p * (1 - p) , rtol=0.035,
+      self.assertAllClose(samples.var(), n * p * (1 - p) , rtol=0.036,
                           check_dtypes=False)
 
   def testBinomialCornerCases(self):