Make mock_mr deallocation noexcept (#2085)

Follow-up to #2077. This change was missed in that PR. Enforcing `noexcept` in CCCL makes the RMM build fail.

xref: #2076

Authors:
  - Bradley Dice (https://github.com/bdice)

Approvers:
  - Lawrence Mitchell (https://github.com/wence-)

URL: #2085

Author: bdice

cpp/tests/mr/device/arena_mr_tests.cpp

@@ -43,9 +43,12 @@ namespace {
 class mock_memory_resource {
  public:
   MOCK_METHOD(void*, allocate, (std::size_t, std::size_t));
-  MOCK_METHOD(void, deallocate, (void*, std::size_t, std::size_t));
+  MOCK_METHOD(void, deallocate, (void*, std::size_t, std::size_t), (noexcept));
   MOCK_METHOD(void*, allocate_async, (std::size_t, std::size_t, cuda::stream_ref));
-  MOCK_METHOD(void, deallocate_async, (void*, std::size_t, std::size_t, cuda::stream_ref));
+  MOCK_METHOD(void,
+              deallocate_async,
+              (void*, std::size_t, std::size_t, cuda::stream_ref),
+              (noexcept));
 
   void* allocate_sync(std::size_t bytes, std::size_t alignment)
   {