v4.2.3

What's Changed

• caller or token owner should be able to approve self as operator for … by @jrkosinski in #407
• Add trailing zeros padding to _toString by @Vectorized in #415
• Add payable gas optimization by @Vectorized in #418

New Contributors

• @KamaDeFi made their first contribution in #400
• @jrkosinski made their first contribution in #407

Full Changelog: v4.2.2...v4.2.3