Update dependency doorkeeper to v5.7.1

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
doorkeeper (changelog)	"5.7.0" -> "5.7.1"

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Release Notes

doorkeeper-gem/doorkeeper (doorkeeper)

### [`v5.7.1`](https://togithub.com/doorkeeper-gem/doorkeeper/blob/HEAD/CHANGELOG.md#571) [Compare Source](https://togithub.com/doorkeeper-gem/doorkeeper/compare/v5.7.0...v5.7.1) - \[[#​1705](https://togithub.com/doorkeeper-gem/doorkeeper/issues/1705)] Add `force_pkce` option that requires non-confidential clients to use PKCE when requesting an access_token using an authorization code

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Configuration

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Code Coverage Report: Only Changed Files listed

Package	Coverage
Overall Coverage	🟢 85%

Minimum allowed coverage is 0%, this run produced 85%