Release v0.21.0 (#2535)

Author: jchengsfx

CHANGELOG.md

@@ -2,14 +2,25 @@
 
 ## Unreleased
 
+## v0.21.0 Beta
+
 ## 🛑 Breaking changes 🛑
 
 - Remove deprecated function `IsValid` from trace/span ID (#2522)
 - Remove accessors for deprecated status code (#2521)
 
+## 💡 Enhancements 💡
+
+- `otlphttp` exporter: Add `compression` option for gzip encoding of outgoing http requests (#2502)
+- Add `ScrapeErrors` struct to `consumererror` to simplify errors usage (#2414)
+- Add `cors_allowed_headers` option to `confighttp` (#2454)
+- Add SASL/SCRAM authentication mechanism on `kafka` receiver and exporter (#2503)
+
 ## 🧰 Bug fixes 🧰
 
 - `otlp` receiver: Sets the correct deprecated status code before sending data to the pipeline (#2521)
+- Fix `IsPermanent` to account for wrapped errors (#2455)
+- `otlp` exporter: Preserve original error messages (#2459)
 
 ## v0.20.0 Beta