Remove the lint about non nullable binding instances

[ValentinVignal]

Fixes https://github.com/creativecreatorormaybenot/performance/issues/18

I used the fix recommended by the flutter team: https://docs.flutter.dev/development/tools/sdk/release-notes/release-notes-3.0.0#your-code

I also run flutter pub get, tell me if you want me to remove those changes

[ValentinVignal]

I can not use _ambiguate if you want but it will be a breaking change. A project that didn't upgrade to flutter 3 won't be able to use the new version of this package. Is that fine ?

[creativecreatorormaybenot]

@ValentinVignal It is not a breaking change since we expect everyone using the package to be on the stable channel of Flutter (this is also what the Pub analysis tool uses).

[ValentinVignal]

@creativecreatorormaybenot fair enough, I removed _ambiguate in https://github.com/creativecreatorormaybenot/performance/pull/19/commits/c57bbd97379bad6cfdc93c8a92a030e766c89a5b

[ValentinVignal]

@creativecreatorormaybenot That is fine, I can do it in this PR. I pushed the changes, tell me if something else needs to be changed.

[creativecreatorormaybenot]

@ValentinVignal Thank you so much for your contribution!

[ValentinVignal]

@creativecreatorormaybenot Is there something else I need to do for it to be merged and released?

[creativecreatorormaybenot]

@ValentinVignal your commits were not signed. But I removed this requirement now as I am going to squash anyway (in which case GitHub will sign the squash commit).