`find_package(GTest REQUIRED CONFIG)` fails on cmake 3.21.4

[shamefulCake1]

GTest support is usually provided by cmake itself by the means of FindGTest.cmake, rather than by gtest using GTestConfig.cmake.

So I am not entirely sure why that like in ospTestSuite is using the CONFIG mode.

Patching CONFIG out just works, but maybe this should be the default?