Update http-grpc to v0.12.6

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
prost	dependencies	patch	0.12.4 -> 0.12.6
prost-types	dependencies	patch	0.12.4 -> 0.12.6

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Release Notes

tokio-rs/prost (prost)

### [`v0.12.6`](https://togithub.com/tokio-rs/prost/compare/v0.12.5...v0.12.6) [Compare Source](https://togithub.com/tokio-rs/prost/compare/v0.12.5...v0.12.6) ### [`v0.12.5`](https://togithub.com/tokio-rs/prost/compare/v0.12.4...v0.12.5) [Compare Source](https://togithub.com/tokio-rs/prost/compare/v0.12.4...v0.12.5)

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