- remove -Werror to unbreak test build
- fix gtest include and library paths

Index: tests/CMakeLists.txt
--- tests/CMakeLists.txt.orig
+++ tests/CMakeLists.txt
@@ -131,7 +131,6 @@ else()
         -Wcast-align
         -Wconversion
         -Wctor-dtor-privacy
-        -Werror
         -Wextra
         -Wpedantic
         -Wshadow
@@ -196,7 +195,7 @@ endif()
 
 # for tests to find the gtest header
 target_include_directories(gsl_tests_config SYSTEM INTERFACE
-    googletest/googletest/include
+    ${GTestMain_INCLUDE_DIRS}
 )
 
 add_executable(gsl_tests
@@ -218,7 +217,7 @@ add_executable(gsl_tests
 target_link_libraries(gsl_tests
     Microsoft.GSL::GSL
     gsl_tests_config
-    ${GTestMain_LIBRARIES}
+    ${GTestMain_LINK_LIBRARIES}
 )
 add_test(gsl_tests gsl_tests)
 
@@ -273,7 +272,6 @@ else()
         -Wcast-align
         -Wconversion
         -Wctor-dtor-privacy
-        -Werror
         -Wextra
         -Wpedantic
         -Wshadow
