deps: bump prometheus-client from 0.19.0 to 0.21.0

[dependabot]

Bumps prometheus-client from 0.19.0 to 0.21.0.

Release notes

Sourced from prometheus-client's releases.

v0.21.0

See changelog for details.

v0.20.0

See changelog for details.

Changelog

Sourced from prometheus-client's changelog.

[0.21.0]

Changed

• Replace impl EncodeMetric for RefCell<T> with a new type ConstFamily implementing EncodeMetric.

[0.20.0]

Added

• Introduce Collector abstraction allowing users to provide additional metrics and their description on each scrape. See PR 82.

• Introduce a #[prometheus(flatten)] attribute which can be used when deriving EncodeLabelSet, allowing a nested struct to be flattened during encoding. See PR 118.

  For example:

  #[derive(EncodeLabelSet, Hash, Clone, Eq, PartialEq, Debug)]
  struct CommonLabels {
      a: u64,
      b: u64,
  }
  #[derive(EncodeLabelSet, Hash, Clone, Eq, PartialEq, Debug)]
  struct Labels {
      unique: u64,
      #[prometheus(flatten)]
      common: CommonLabels,
  }

  Would be encoded as:

  my_metric{a="42",b="42",unique="42"} 42
  

Fixed

• Fix label encoding in protobuf feature. See PR 123.

Commits

• 2649447 refactor(family): introduce ConstFamily type (#138)
• 85033bf chore: prepare v0.20.0 (#133)
• e35e99d fix(protobuf): Do not share label storage across families (#123)
• 51de116 build(deps): update pyo3 requirement from 0.17 to 0.18 (#127)
• 9141c11 feat(derive): Introduce flatten attribute (#118)
• c619ad5 feat!: Introduce Collector abstraction (#82)
• 2f72a1b chore(.github): Include token to prevent protoc rate limiting (#121)
• See full diff in compare view

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[dependabot]

Superseded by #165.