Update dependency http to ^0.13.0

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
http	dependencies	minor	^0.12.1 -> ^0.13.0

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Release Notes

dart-lang/http

### [`v0.13.0`](https://togithub.com/dart-lang/http/blob/master/CHANGELOG.md#​0130) [Compare Source](https://togithub.com/dart-lang/http/compare/0.12.2...0.13.0) - Stable null safety release.

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