fix: Pubspec.environment can never be null

[spydon]

Since Pubspec.environment defaults to an empty map in the initializer list it can never be null.

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[spydon]

@kevmoo could you have a look at this oneliner? 🙏

[kevmoo]

Let's see what the CI says, @spydon 😀

[spydon]

Let's see what the CI says, @spydon 😀

I removed the deprecated rule here: #141

[kevmoo]

thanks for fixing the rule.
Please update the changelog

[spydon]

thanks for fixing the rule. Please update the changelog

Done! I'm so used to that the changelog is generated from the conventional commits. 😜

[kevmoo]

you'll need to run dart run build_runner build