Automate releases using a script
- [x] modify version number
- [x] tag
- [x] Generate Pyinstaller build
- [x] Generate sha256 checksum file
Release scripts examples:
- [Duniter](https://github.com/duniter/duniter/blob/master/release.sh)
- [Sakia](https://github.com/duniter/sakia/blob/master/release.sh)
- [Cesium](https://github.com/duniter/cesium/blob/master/release.sh)
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