3.0.4 - Fixed C++20 compatibility

Changes:

• Fixed C++20 compatibility with some compilers (kudos @RoqueDeicide for #61 and @TaeZStkyoht for #62)

Description:

C++20 deprecated std::result_of, but some couplers like GCC kept it for some reason. We started to use our own implementation or result_of variadic template and declared it in our own sub-namespace to avoid collisions in case of using both std and boolinq.

3.0.3

• Improved compatibility with C++20 (introduced result_of)