Update dependency pigeon to v28 - autoclosed

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
pigeon (source)	dev_dependencies	major	^27.0.0 → ^28.0.0

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Release Notes

flutter/packages (pigeon)

v28.1.0

Compare Source

• [swift] Adds support for multiple output locations in swiftOut and --swift_out.

v28.0.0

Compare Source

• Breaking Change Updates Kotlin and Swift generators to generate suspend functions and async throws signatures for @FlutterApi methods by default, and for @HostApi methods annotated with @async.
  • Use @asyncCallback if callback-style signatures are required.

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