Replace hard-coded version number with http_version variable

[rajkumardongre]

No description provided.

[interkosmos]

Maybe, we turn it into a public parameter within a distinct file, for example, http_version.f90? Furthermore, we could create the version string on compile time:

    integer, parameter, public :: VERSION_MAJOR = 0
    integer, parameter, public :: VERSION_MINOR = 1

    character(len=*), parameter, public :: VERSION_STRING = achar(VERSION_MAJOR + 48) // '.' // achar(VERSION_MINOR + 48)

Just an idea.

[rajkumardongre]

This approach looks good, I will make the changes