v0.13.0

• Bump MSRV to 1.56.0
• Add build_fn(error(validation_error = <bool>)) to disable generation of ValidationError within the builder's error so that alloc::string is avoided.
• Add feature alloc for controlling linking of alloc crate during no_std. This way users can use no_std without providing a global_allocator.
• Make try-setters inherit strip_option from setter for try_setter. Using these settings together previously caused a compile error #284