fix(deps): update module github.com/golang/protobuf to v1.5.4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
github.com/golang/protobuf	v1.5.2 -> v1.5.4

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Release Notes

golang/protobuf (github.com/golang/protobuf)

### [`v1.5.4`](https://togithub.com/golang/protobuf/releases/tag/v1.5.4) [Compare Source](https://togithub.com/golang/protobuf/compare/v1.5.3...v1.5.4) Notable changes - update descriptor.proto to latest version ### [`v1.5.3`](https://togithub.com/golang/protobuf/releases/tag/v1.5.3) [Compare Source](https://togithub.com/golang/protobuf/compare/v1.5.2...v1.5.3) Notable changes \*( [#​1363](https://togithub.com/golang/protobuf/issues/1363)) jsonpb: accept 'null' as a valid representation of NullValue in unmarshal

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