Update opentelemetry-specification version to 1.28.0

[opentelemetrybot]

Update opentelemetry-specification version to 1.28.0.

See https://github.com/open-telemetry/opentelemetry-specification/releases/tag/v1.28.0.

[svrnm]

WARNINGs or ERRORs found in build log:
ERROR [en] REF_NOT_FOUND: Ref "/docs/specs/semconv/general/attribute-naming.md": "/home/runner/work/opentelemetry.io/opentelemetry.io/tmp/otel/specification/common/attribute-naming.md:6:83": page not found
ERROR [en] REF_NOT_FOUND: Ref "/docs/specs/semconv/general/attribute-requirement-level.md": "/home/runner/work/opentelemetry.io/opentelemetry.io/tmp/otel/specification/common/attribute-requirement-level.md:6:94": page not found
ERROR [en] REF_NOT_FOUND: Ref "/docs/specs/semconv/general/attribute-naming.md": "/home/runner/work/opentelemetry.io/opentelemetry.io/tmp/otel/specification/common/_index.md:44:24": page not found
ERROR [en] REF_NOT_FOUND: Ref "/docs/specs/semconv/general/attribute-requirement-level.md": "/home/runner/work/opentelemetry.io/opentelemetry.io/tmp/otel/specification/common/_index.md:46:25": page not found
Error: error building site: logged 4 error(s)

[svrnm]

@open-telemetry/specs-approvers , @open-telemetry/specs-semconv-approvers please take a look here. The latest release of the spec is referencing elements of the semantic conventions which have not yet been released, breaking links in this commit:

To be more specific: Attribute Naming & Attribute Requirement Level files were moved to semconv, but that part is not released with semconv

Are there any plans to provide a new release of semconv as well?

[chalin]

We might have to wait and update both the OTel spec and Semconv at the same time, as we have done at least once in the past (as you might recall):

• Update to spec 1.26.0 and semconv 1.22.0 at the SAME time #3388