Update dependency prom-client to v15

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
prom-client	^14.2.0 -> ^15.0.0

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Release Notes

siimon/prom-client (prom-client)

v15.0.0

Compare Source

Breaking

• drop support for Node.js versions 10, 12, 14, 17 and 19

Changed

• Refactor histogram internals and provide a fast path for rendering metrics to
  Prometheus strings when there are many labels shared across different values.
• Disable custom content encoding for pushgateway delete requests in order to
  avoid failures from the server when using Content-Encoding: gzip header.
• Refactor escapeString helper in lib/registry.js to improve performance and
  avoid an unnecessarily complex regex.
• Cleanup code and refactor to be more efficient
• Correct TS types for working with OpenMetrics
• Updated Typescript and Readme docs for setToCurrentTime() to reflect units as seconds.
• Do not ignore error if request to pushgateway fails
• Make sure to reject the request to pushgateway if it times out

Added

• Support for OpenMetrics and Exemplars

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