Update changelog and version of CVAT server

CHANGELOG.md

@@ -5,7 +5,27 @@ 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).
 
-## [1.2.0] - 2020-11-09
+## [1.2.0-beta] - Unreleased
+
+### Added
+-
+
+### Changed
+-
+
+### Deprecated
+-
+
+### Removed
+-
+
+### Fixed
+-
+
+### Security
+-
+
+## [1.2.0-alpha] - 2020-11-09
 
 ### Added
 - Ability to login into CVAT-UI with token from api/v1/auth/login (<https://github.com/openvinotoolkit/cvat/pull/2234>)

cvat/__init__.py

@@ -4,6 +4,6 @@
 
 from cvat.utils.version import get_version
 
-VERSION = (1, 2, 0, 'alpha', 0)
+VERSION = (1, 2, 0, 'beta', 0)
 
 __version__ = get_version(VERSION)