switch to C++17 following the core library (#7116)

Co-authored-by: vfdev <vfdev.5@gmail.com>

CMakeLists.txt

-cmake_minimum_required(VERSION 3.12)
+cmake_minimum_required(VERSION 3.18)
 project(torchvision)
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 17)
 file(STRINGS version.txt TORCHVISION_VERSION)
 
 option(WITH_CUDA "Enable CUDA support" OFF)
@@ -13,11 +13,6 @@ if(WITH_CUDA)
   add_definitions(-D__CUDA_NO_HALF_OPERATORS__)
   add_definitions(-DWITH_CUDA)
   set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} --expt-relaxed-constexpr")
-  # CUDA-11.x can not be compiled using C++14 standard on Windows
-  string(REGEX MATCH "^[0-9]+" CUDA_MAJOR ${CMAKE_CUDA_COMPILER_VERSION})
-  if(${CUDA_MAJOR} GREATER 10 AND MSVC)
-    set(CMAKE_CXX_STANDARD 17)
-  endif()
 endif()
 
 find_package(Torch REQUIRED)