Unbreak custom_kernel_example test (#7985)

This test doesn't run in OSS CI (#7984), so I missed it.

Test Plan: ran relevant test internally with buck2

Author: swolchok

kernels/test/custom_kernel_example/op_relu.cpp

@@ -79,7 +79,7 @@ my_relu_out(KernelRuntimeContext& context, const Tensor& input, Tensor& out) {
     break;
 
   switch (input.scalar_type()) {
-    ET_FORALL_REAL_TYPES(RELU)
+    ET_FORALL_REALHBF16_TYPES(RELU)
     default:
       ET_KERNEL_CHECK_MSG(
           context,