Merge pull request #18 from lzchen/prepare-release-1.13.0-0.33b0

[release/v1.13.x-0.33bx] Prepare release 1.13.0/0.33b0

Author: lzchen

CHANGELOG.md

@@ -5,7 +5,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## Unreleased
+## Version 1.13.0/0.33b0 (2022-06-15)
 
 - Add min/max fields to Histogram
   ([#2759](https://github.com/open-telemetry/opentelemetry-python/pull/2759))