Release version 1.3.1

Added
* Testing proxy - moved from Minipots repository
* CHANGELOG

Changed
* Complete code refactoring - replace `zpoller` by `zloop`

CHANGELOG.md

@@ -4,7 +4,7 @@ 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).
 
-## Unreleased
+## [1.3.1] - 2021-02-01
 ### Added
 - Testing proxy - moved from Minipots repository
 - CHANGELOG

configure.ac

-AC_INIT([sentinel-proxy], [1.3], [])
+AC_INIT([sentinel-proxy], [1.3.1], [])
 
 AM_INIT_AUTOMAKE([foreign -Wall -Wno-portability])
 AC_PROG_CC