- fix gtest include dir
- link correct libs

Index: tests/CMakeLists.txt
--- tests/CMakeLists.txt.orig
+++ tests/CMakeLists.txt
@@ -201,7 +201,7 @@ endif()
 
 # for tests to find the gtest header
 target_include_directories(gsl_tests_config SYSTEM INTERFACE
-    googletest/googletest/include
+    /usr/local/include
 )
 
 # Individually build and register each test source (except no_exception_ensure_tests.cpp)
@@ -215,7 +215,7 @@ foreach(src IN LISTS GSL_TEST_SOURCES)
   target_link_libraries(${test_name}
     Microsoft.GSL::GSL
     gsl_tests_config
-    ${GTestMain_LIBRARIES}
+    ${GTestMain_LINK_LIBRARIES}
   )
   add_test(NAME ${test_name} COMMAND ${test_name})
   set_target_properties(${test_name} PROPERTIES FOLDER "tests")
