Add slight tolerance term in _check_hypercube (#2679)

Summary:
Pull Request resolved: #2679

#thanks saitcakmak for helping me debug this

Reviewed By: saitcakmak, SebastianAment

Differential Revision: D68229394

fbshipit-source-id: c9a32dea4c46813f1a48ed3a014f26d3c557f588

Author: mpolson64

botorch/models/kernels/orthogonal_additive_kernel.py

@@ -336,7 +336,8 @@ def _check_hypercube(x: Tensor, name: str) -> None:
         x: Tensor to be checked.
         name: Name of the Tensor for the error message.
     """
-    if (x < 0).any() or (x > 1).any():
+    tolerance = 1e-6
+    if (x < -1 * tolerance).any() or (x > 1 + tolerance).any():
         raise ValueError(name + " is not in hypercube [0, 1]^d.")