Const and no excepts fixed for the scope guard strategies.

include/scope_exit.h

 
         struct scope_exit_strategy
         {
-            constexpr bool should_execute() const
+            bool should_execute() const noexcept
             {
                 return true;
             }

include/scope_fail.h

 
         struct scope_fail_strategy
         {
-            bool should_execute() const
+            bool should_execute() const noexcept
             {
                 return uncaught_exceptions() > m_uncaught_on_creation;
             }

include/scope_success.h

 
         struct scope_success_strategy
         {
-            bool should_execute() const
+            bool should_execute() const noexcept
             {
                 return uncaught_exceptions() <= m_uncaught_on_creation;
             }