Bump version to 1.5.0

[edisonhello]

Since there're some bug fixes and performance improvements, I don't know if you want to upgrade the library to the 1.5.0 version.

By the way, I realized that the .clang-format file isn't properly used in the script clang-format.bash (which uses an inlined style when calling clang-format). Do you have any preference about which one to keep?

[p-ranav]

Thanks! Yes, I agree it's time for 1.5.0. I think I prefer the clang-format.bash version with a 100 column limit. Perhaps we can simply change the .clang-format file to match it, so that there isn't this inconsistency.

[edisonhello]

Sure. .clang-format and the script clang-format.bash are both updated. Also, I avoid the script from formatting the {variant,string_view,optional}_lite.hpp files as they are actually external files.