feat: add support for UTF-8 and new UTF-8 related validators

[FUSAKLA]

fixes #88

• enable UTF-8 support in label and metric names by default
• add validator to disallow using the UTF-8 (this should be used as a default for now, UTF-8 support is still in early stages in Prometheus)

this change will probably result into new major version, since the UTF-8 support might be breaking

Signed-off-by: Martin Chodur [email protected]

[FUSAKLA]

@jmichalek132 would you give it a try? 🙏

[jmichalek132]

FYI with Prometheus 3.X UTF-8 support is enabled by default, but some backends like Mimir / Cortex / Thanos might not support it yet.

[jmichalek132]

Suggested change

	- Change: :warning: Enable UTF-8 support in metic and label names by default. To disallow usage of UTF-8 characters in metric and label names use the new validator [`doesNotUseUTF8`](./docs/validations.md#doesnotuseutf8).
	- Change: :warning: Enable UTF-8 support in metric and label names by default. To disallow usage of UTF-8 characters in metric and label names use the new validator [`doesNotUseUTF8`](./docs/validations.md#doesnotuseutf8).

[jmichalek132]

LGTM, 2 small comments left.

[jmichalek132]

Given the UTF-8 support was added to better support OTEL metrics, and the only character that was not allowed in Prometheus but is commonly used in OTEL is dot, it might be worth considering adding a validation that allows Prometheus charset + dot, without allowing other UTF-8 characters.

[ywwg]

is there a reason to add this specific type of utf8 character as opposed to any of the other blocks? It seems arbitrary. (Why not also exclude arrows or other symbols?)