Cut v2.19.3 (#7657)

Signed-off-by: NGanesh Vernekar <cs15btech11018@iith.ac.in>

CHANGELOG.md

+## 2.19.3 / 2020-07-24
+
+* [BUGFIX] TSDB: Don't panic on WAL corruptions. #7550
+* [BUGFIX] TSDB: Avoid leaving behind empty files in chunks_head, causing startup failures. #7573
+
 ## 2.19.2 / 2020-06-26
 
 * [BUGFIX] Remote Write: Fix panic when reloading config with modified queue parameters. #7452

VERSION

-2.19.2
+2.19.3