Custom `dist` overrides version build number

[denrase]

:scroll: Description

When a custom dist is provided, either though pubspec or env variable, it takes precedence over the versions build number.

:bulb: Motivation and Context

Closes #210

:green_heart: How did you test it?

Unit tests

:pencil: Checklist

• [x] I reviewed submitted code
• [x] I added tests to verify changes
• [ ] I updated the docs if needed
• [x] All tests passing
• [x] No breaking changes

[buenaflor]

@denrase looks good here if you wanna merge