separate arg with = so sccache works with nvc++

CMakeLists.txt

@@ -201,7 +201,7 @@ target_compile_options(stdexec_executable_flags INTERFACE
                           $<$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},MSVC>:/clang:>-fmacro-backtrace-limit=0
                           $<$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},MSVC>:/clang:>-ftemplate-backtrace-limit=0>
                        $<$<AND:$<CXX_COMPILER_ID:NVHPC>,$<VERSION_GREATER:$<CXX_COMPILER_VERSION>,23.3.0>>:
-                       -ftemplate-backtrace-limit 0>)
+                       -ftemplate-backtrace-limit=0>)
 
 # # Always enable colored output
 # target_compile_options(stdexec_executable_flags INTERFACE