Fix warning C4251: class fmt::v8::file needs to have dll-interface (#2797)

* Fix warning C4251: class fmt::v8::file needs to have dll-interface

* Add CMake target dependency between test-main and fmt

test/CMakeLists.txt

@@ -4,7 +4,7 @@ set(TEST_MAIN_SRC test-main.cc gtest-extra.cc gtest-extra.h util.cc)
 add_library(test-main STATIC ${TEST_MAIN_SRC})
 target_include_directories(test-main PUBLIC
   $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>)
-target_link_libraries(test-main gtest)
+target_link_libraries(test-main gtest fmt)
 
 include(CheckCXXCompilerFlag)