Version number update

[sos4nt]

I've just noticed, that the current version number (0.1.1) still starts with a zero, indicating a development version with unstable public API. Since this is rather mature code, you might consider a 1.x release (or 3.x to match Ruby).

[hsbt]

indicating a development version with unstable public API.

I know a few people rely on this policy. But base64 don't use this versioning policy. You can use 0.x.y for produciton use.

[perlun]

I also noted this @sos4nt. 🤔 Since SemVer is so prevalent (and IMO for good reasons), perhaps adding a note about the fact you describe here to the top-level README file would make sense @hsbt? Just to minimize the confusion.

(I got here since I ran into the warning that base64 will no longer be included in the standard gems in Ruby 3.4, triggered by this lib in my dependency graph: dtao/safe_yaml#108)