Bump version: 2.19.3 [ci skip]

Author: jianghao0718

debian/changelog

@@ -1,3 +1,9 @@
+github-backup-utils (2.19.3) UNRELEASED; urgency=medium
+
+  * Fix two issues with binary backup (slow gzip compression and support for restore from instances other than SQL master) #551
+
+ -- Hao Jiang <[email protected]>  Tue, 11 Feb 2020 19:31:55 +0000
+
 github-backup-utils (2.19.2) UNRELEASED; urgency=medium
 
   * Fix `ghe-backup-repositories` performance for large instances #541