chore(deps): update rust crate metrics to v0.24.6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
metrics	dependencies	patch	0.24.3 → 0.24.6

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Release Notes

metrics-rs/metrics (metrics)

v0.24.6

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v0.24.5

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v0.24.4

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[doubleword-code]

Summary

This PR updates the metrics crate from v0.24.3 to v0.24.6 via a Cargo.lock refresh. This is a routine dependency maintenance change managed by Renovate.

Verdict: Ready to approve — no code changes required.

The update includes three minor versions (0.24.4, 0.24.5, 0.24.6) with internal improvements and bug fixes that do not affect the API surface used by this crate. The Cargo.toml already specifies metrics = "0.24", so this update is within the allowed semver range.

Research notes

Fetched the official changelog from metrics-rs/metrics CHANGELOG.md:

Key changes between 0.24.3 → 0.24.6:

0.24.6 (2026-05-13):

• Added: Support for description and unit parameters in counter!, gauge!, histogram! macros
• Fixed: Regression in KeyHasher causing Registry to insert fresh entries after HashMap resize (#694)

0.24.5 (2026-04-29):

• Fixed: Regression where hash_label hashed the label key twice, potentially causing label collisions (#690)

0.24.4 (2026-04-28):

• Changed: Internal key hasher swapped from ahash to rapidhash for faster, allocation-free hashing (#651, #669)
• Changed: Key hash now computed eagerly at construction, removing internal atomics (#669)
• Deprecated: metrics::KeyHasher (use metrics_util::common::KeyHasher instead)
• Added: Key::to_retained(), KeyName::to_retained() methods, const fn improvements

Impact analysis for outlet-postgres:

This crate uses metrics minimally:

• Import: use metrics::{counter, histogram}; (line 85)
• Usage: Simple counter!() and histogram!() macro calls for instrumentation (lines 497, 548, 640, 709)

The codebase does not use:

• Custom key hashing (KeyHasher)
• Complex label manipulation that could be affected by the hash_label fix
• The deprecated types being removed

The API surface used remains stable and backward-compatible.

Suggested next steps

1. Approve and merge — This is a safe, routine dependency update with no code changes needed.
2. Consider running integration tests in CI to confirm metrics recording behaves as expected (standard practice for any dependency update).

General findings

No issues identified. The change is exactly what it claims to be: a patch-level dependency update within an already-specified semver range. The metrics crate's changelog confirms these are internal improvements and bug fixes that don't affect the simple metric recording patterns used in this codebase.