refactor: Add pubspec in dart example

[mbfakourii]

Pull Request

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• Link this pull request to an issue.

Issue

add pubspec in dart example and fix main.dart example warning

Closes: #905

Approach

n/a

Tasks

n/a

• [ ] Add tests
• [ ] Add changes to documentation (guides, repository pages, code comments)

[parse-github-assistant[bot]]

I will reformat the title to use the proper commit message syntax.

[parse-github-assistant[bot]]

Thanks for opening this pull request!

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: +2.74 :tada:

Comparison is base (7bfce0f) 39.13% compared to head (1a0ebad) 41.88%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #908 +/- ## ========================================== + Coverage 39.13% 41.88% +2.74% ========================================== Files 56 51 -5 Lines 3278 2994 -284 ========================================== - Hits 1283 1254 -29 + Misses 1995 1740 -255 ``` [see 5 files with indirect coverage changes](https://app.codecov.io/gh/parse-community/Parse-SDK-Flutter/pull/908/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community)

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[mtrezza]

It's a fix in the example, which is not part of the SDK itself, so this is merely a refactor and won't cause a release.

[mbfakourii]

Looks good, ready for merge?

Yes, I think it is ready

[Nidal-Bakir]

Could you run the following command to see if there are any errors: dart analyze packages/dart --fatal-infos

[Nidal-Bakir]

I just tested it with dart analyze packages/dart --fatal-infos no issues were found. We are good to publish Dart 5.1.1

[Nidal-Bakir]

See https://github.com/parse-community/Parse-SDK-Flutter/pull/906#issuecomment-1554221396

[mtrezza]

Can this PR be merged despite the failing CI?

[mbfakourii]

Can this PR be merged despite the failing CI?

This error is related to the version of Flutter, merge it and there will be no problem