swift-protobuf 1.28.1

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Created by brew bump

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Created with brew bump-formula-pr.

release notes

This is a follow up that addresses some issues in the generated code when using access levels on imports.
What's Changed

Fix Foundation import's access level in generated code by @gjcairo in Fix Foundation import's access level in generated code apple/swift-protobuf#1701
Less generation when no messages, enums, or extensions. by @thomasvl in Less generation when no messages, enums, or extensions. apple/swift-protobuf#1703
Conditional foundation import by @thomasvl in Conditional foundation import apple/swift-protobuf#1704
Missed comments on Conditional foundation import apple/swift-protobuf#1704. by @thomasvl in Missed comments on https://github.com/apple/swift-protobuf/pull/1704. apple/swift-protobuf#1705
Revert "Pin docc to a version that works for older swift versions." by @thomasvl in Revert "Pin docc to a version that works for older swift versions." apple/swift-protobuf#1706
Revise empty file support for import public by @thomasvl in Revise empty file support for import public apple/swift-protobuf#1707
Version bump for a release. by @thomasvl in Version bump for a release. apple/swift-protobuf#1708

Full Changelog: apple/swift-protobuf@1.28.0...1.28.1

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