make float 8 error message test BC (#1284)

this test is going to fail on older versions of pytorch, i.e. https://github.com/pytorch/ao/actions/runs/11827805971/job/32956667984?pr=1282
we can make this handle both old/current by being slightly less specific with the error check

Author: HDCharles

test/float8/test_base.py

@@ -632,7 +632,7 @@ def test_pad_inner_dim(self, base_dtype, use_fast_accum):
         with pytest.raises(
             RuntimeError,
             match=re.escape(
-                "Expected trailing dimension of mat1 to be divisible by 16 but got mat1 shape: (16x41)."
+                "Expected trailing dimension of mat1 to be divisible by 16 but got mat1 shape: (16x41"
             ),
         ):
             a_fp8 @ b_fp8