Release 6.1.1

[p-avital]

• Add support for multi-fields variants in repr(C, u*) enums.
  • Deprecate support for repr(C) by deprecating any enum that uses it without also specifying a determinant size.
• Add support for Result<T, core::conver::Infallible>, which is fully identical to T down to its reports.
• Remove CompilerVersion_X_Y_Z types: keeping them up to date with new compiler release was too much maintenance.
• Remove CurrentCompilerVersion type alias: as it could break your code if you upgraded to a version of the compiler that stabby didn't know of.
• Prepare integration of stabby and safer-ffi by adding CType and is_invalid to IStable.
• Switch versioning system to SemVer Prime, using the api, abi as the key.
• RFC 3633 which seeks to address the breaking change in Rust 1.78 is scheduled to be discussed in July 2024.