fix(deps): update dependency prometheus-client to ^0.20.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
prometheus-client	^0.19.0 -> ^0.20.0

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Release Notes

prometheus/client_python (prometheus-client)

### [`v0.20.0`](https://togithub.com/prometheus/client_python/releases/tag/v0.20.0): 0.20.0 / 2024-02-14 [Compare Source](https://togithub.com/prometheus/client_python/compare/v0.19.0...v0.20.0) #### What's Changed - \[CHANGE/BUGFIX] Update OpenMetrics Content Type to 1.0.0. [#​997](https://togithub.com/prometheus/client_python/issues/997) - \[FEATURE] Enable graceful shutdown for start\_{http,wsgi}\_server by returning the server and thread. [#​999](https://togithub.com/prometheus/client_python/issues/999) - \[FEATURE] Allow resetting counter metrics. [#​1005](https://togithub.com/prometheus/client_python/issues/1005) - \[BUGFIX] wsgi server: address family discovery is not quite right. [#​1006](https://togithub.com/prometheus/client_python/issues/1006)

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