v3.1.1

What's Changed

• Technical/Refactor performance issue by @bestwebua in #273
• Technical/Update license by @bestwebua in #272
• Technical/Refactor valid? predicate by @bestwebua in #275
• Technical/Update gem development dependencies by @bestwebua in #276
• Technical/Update gem version by @bestwebua in #277
• Truemail v3.1.1 by @bestwebua in #278

Full Changelog: v3.1.0...v3.1.1