chore: prepare for the next release

[tisonkun]

No description provided.

[Copilot]

Pull request overview

This PR prepares the workspace for the next release by bumping crate versions, updating changelogs, and adjusting the logging example to the newer logforth API/features.

Changes:

• Bumped fastrace family crate versions to 0.7.18 and fastrace-opentelemetry to 0.18.1, including workspace dependency pin updates.
• Added release headers to the root and fastrace-opentelemetry changelogs for the new versions.
• Upgraded the examples’ logforth dependency and updated examples/logging.rs to use starter_log + fastrace diagnostics/layout.

Reviewed changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
fastrace/Cargo.toml	Bumps fastrace crate version to 0.7.18.
fastrace-macro/Cargo.toml	Bumps fastrace-macro crate version to 0.7.18.
fastrace-jaeger/Cargo.toml	Bumps fastrace-jaeger crate version to 0.7.18.
fastrace-datadog/Cargo.toml	Bumps fastrace-datadog crate version to 0.7.18.
fastrace-futures/Cargo.toml	Bumps fastrace-futures crate version to 0.7.18.
fastrace-opentelemetry/Cargo.toml	Bumps fastrace-opentelemetry crate version to 0.18.1.
Cargo.toml	Updates workspace dependency versions for fastrace and fastrace-macro to 0.7.18.
CHANGELOG.md	Adds v0.7.18 section header.
fastrace-opentelemetry/CHANGELOG.md	Adds v0.18.1 section header.
examples/Cargo.toml	Upgrades logforth to 0.30.1 and updates enabled features.
examples/logging.rs	Updates example logger setup to the newer logforth::starter_log + fastrace diagnostics/layout API.
Cargo.lock	Refreshes lockfile to reflect the new versions and dependency graph changes (notably logforth).

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