Update gtest from release-1.10.0 -> release-1.12.0. NFC

[sbc100]

On my machine this fixes the following error:

In file included from /usr/local/google/home/sbc/dev/wasm/wabt/third_party/gtest/googletest/src/gtest-all.cc:42:
/usr/local/google/home/sbc/dev/wasm/wabt/third_party/gtest/googletest/src/gtest-death-test.cc:1385:26: error: unknown type name 'uintptr_t'; did you mean 'intptr_t'?
 1385 |         reinterpret_cast<uintptr_t>(stack_top) % kMaxStackAlignment == 0);
      |                          ^~~~~~~~~
      |                          intptr_t
/usr/local/google/home/sbc/dev/wasm/wabt/third_party/gtest/googletest/src/gtest-death-test.cc:308:38: note: expanded from macro 'GTEST_DEATH_TEST_CHECK_'
  308 |     if (!::testing::internal::IsTrue(expression)) { \
      |                                      ^
/usr/include/unistd.h:267:20: note: 'intptr_t' declared here
  267 | typedef __intptr_t intptr_t;
      |                    ^
1 error generated.
[37/40] Building CXX object CMakeFiles/wabt-unittests.dir/src/test-interp.cc.o