v6.7.10: Improvements on "children" prop and fix "replace" behaviour bug

🐛 Fixes or improvements

• Fixed bug that shows files as non valid when Dropzone props are set behaviour="replace" and user drops more files than the maxFiles prop.
• Improved children prop behaviour: Since version 6.7.10 children prop has the highest priority and will show the children content if present even when thee is no dropped files.
• Package now can be used in react 17 and 18 ⚛️ 🚀