wrap-up before new release

+ README: update version number in the badge
+ version: update fall back release version number and date

docs/README.md

@@ -1,7 +1,7 @@
 [![Language](https://img.shields.io/badge/python-3.5%2B-blue.svg)](https://www.python.org/)
 [![Docs Status](https://readthedocs.org/projects/mintpy/badge/?version=latest)](https://mintpy.readthedocs.io/?badge=latest)
 [![CircleCI](https://img.shields.io/circleci/build/github/insarlab/MintPy.svg?color=green&logo=circleci)](https://circleci.com/gh/insarlab/MintPy)
-[![Latest version](https://img.shields.io/badge/latest%20version-v1.2.2-yellowgreen.svg)](https://github.com/insarlab/MintPy/releases)
+[![Latest version](https://img.shields.io/badge/latest%20version-v1.2.3-yellowgreen.svg)](https://github.com/insarlab/MintPy/releases)
 [![License](https://img.shields.io/badge/license-GPLv3-yellow.svg)](https://github.com/insarlab/MintPy/blob/master/LICENSE)
 [![Forum](https://img.shields.io/badge/forum-Google%20Group-orange.svg)](https://groups.google.com/forum/#!forum/mintpy)
 [![Citation](https://img.shields.io/badge/doi-10.1016%2Fj.cageo.2019.104331-blue)](https://doi.org/10.1016/j.cageo.2019.104331)

mintpy/version.py

@@ -5,7 +5,7 @@
 
 
 ###########################################################################
-def get_release_info(version='v1.2.2', date='2020-04-27'):
+def get_release_info(version='v1.2.3', date='2020-07-14'):
     """Grab version and date of the latest commit from a git repository"""
     # go to the repository directory
     dir_orig = os.getcwd()