Null safety update

[inowakowski]

Hello, I would like to use this package in my application. However, the latest flutter rejects due to the fact that the package is not Null safety. Can you please update it. I have seen online that this can supposedly be done quickly.

[danielle-h]

I would love this update as well :)

[netgfx]

I can fix the null safety, does the project accept PRs?

[andrewmd5]

I can fix the null safety, does the project accept PRs?

we do

[gyenesvi]

I'm trying to use this too, but it does not work due to lack of null safety. @AndrewMD5 the pull request seems to be there, could you take the time to review it and update the package? Otherwise this package is more complicated to use for now (the only way seems to be running flutter with the --no-sound-null-safety option).