Release 0.3.1

See #42, release log:

• 61569ac by @rultor: version 0.3.1
• bc45906 by @rafamizes: doc(README): fix formatting an...
• a3b0737 by @rafamizes: Update README.md
• 7445f5b by @rafamizes: Update README.md
• 6d43a76 by @rafamizes: Update README.md
• 3cb0028 by @rafamizes: feat: JsonCacheCrossLocalStora...
• 326f238 by @rafamizes: style: pub dev fixes * refacto...

Released by Rultor 1.70.1, see build log