fix windows test (facebookresearch#2862)

Summary:
Pull Request resolved: facebookresearch#2862

Fix windows test introduced by range search diff

Reviewed By: algoriddle

Differential Revision: D45901726

fbshipit-source-id: 16259b7718f1409adef814ea4c2b5707304849ca

Author: mdouze

tests/test_build_blocks.py

@@ -701,7 +701,7 @@ def do_test(self, capacity, n):
         """ test that we are able to lookup """
         rs = np.random.RandomState(123)
         # make sure we have unique values
-        keys = np.unique(rs.choice(2 ** 29, size=n))
+        keys = np.unique(rs.choice(2 ** 29, size=n).astype("int64"))
         rs.shuffle(keys)
         n = keys.size
         vals = rs.choice(2 ** 30, size=n).astype('int64')