Release version 0.20.0 - Release Candidate for 1.0.0

This is release 0.20.0. It is a release candidate for upcoming 1.0.0.

What's Changed

Maturity

• Declare OTLP/JSON Stable. (#436) (#435)
• Provide stronger symbolic stability guarantees. (#432)
• Clarify how additive changes are handled. (#455)

Changed

• Change the exponential histogram boundary condition. (#409)
• Clarify behavior for empty/not present/invalid trace_id and span_id fields. (#442)
• Change the collector trace endpoint to /v1/traces. (#449)

Added

• Introduce zero_threshold field to ExponentialHistogramDataPoint. (#441) (#453)

Removed

• Delete requirement to generate new trace/span id if an invalid id is received. (#444)

Full Changelog: v0.19.0...v0.20.0