message: Fix typo in ranges_options.cmake
diff: include(CMakeDependentOption)
  set(RANGES_CXX_STD 11 CACHE STRING "C++ standard version.")
  -option(RANGE_BUILD_CALENDAR_EXAMPLE "Builds the calendar example." ON)
  +option(RANGES_BUILD_CALENDAR_EXAMPLE "Builds the calendar example." ON)
  option(RANGES_ASAN "Run the tests using AddressSanitizer." OFF)
  option(RANGES_MSAN "Run the tests using MemorySanitizer." OFF)
  option(RANGES_ASSERTIONS "Enable assertions." ON)
  