migrate to null-safety this great project

[ghost]

Hi @hemanta212 ,

Hope you are all well ! and happy new year !

I was wondering that it would be awesome to migrate to full support of null-safety for this project and update firebase packages ^^

Thanks for any inputs or insights about that.

Cheers, Luc

[hemanta212]

Hi, Thanks for taking an interest and filing the issue, I understand the need to do the changes you mentioned.

However, while this repo may be helpful for others to learn I have not been able to actually use it practically day to day. I am occupied with other things so might be a little hard for me to do.

On a positive note, I am revising my flutter-fu and working on my other flutter project so I'll definitely consider keeping this issue open and working on it then. If you or anyone steps up to do it I will be more than happy to review and accept a PR so feel free to do it.