Update Rust crate opentelemetry to 0.20

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
opentelemetry	dev-dependencies	minor	0.19 -> 0.20
opentelemetry	dependencies	minor	0.19 -> 0.20

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Release Notes

open-telemetry/opentelemetry-rust (opentelemetry)

### [`v0.20.0`](https://togithub.com/open-telemetry/opentelemetry-rust/releases/tag/v0.20.0) [Compare Source](https://togithub.com/open-telemetry/opentelemetry-rust/compare/v0.19.0...v0.20.0) See individual crate changelogs for details.

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