Update module prometheus/client_golang to v1.9.0

This MR contains the following updates:

Package	Type	Update	Change
github.com/prometheus/client_golang	require	minor	v1.8.0 -> v1.9.0

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Release Notes

prometheus/client_golang

v1.9.0

Compare Source

• [FEATURE] NewPidFileFn helper to create process collectors for processes whose PID is read from a file. #​804
• [BUGFIX] promhttp: Prevent endless loop in InstrumentHandler... middlewares with invalid metric or label names. #​823

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