Increment YDB CLI version to 2.20.0 (#15349)

ydb/apps/ydb/CHANGELOG.md

@@ -1,3 +1,6 @@
+
+## 2.20.0 ##
+
 * Added support for dual configuration mode in the `ydb admin cluster config fetch` command, allowing it to handle separate cluster and storage config sections.
 * Add options for client certificates in SSL/TLS connections.
 * Add `ydb admin node config init` command to initialize directory with node config files.

ydb/apps/ydb/version.txt

@@ -1 +1 @@
-2.19.0
+2.20.0