Dkb-robo

**Improvements**:

- scan_postbox() is able to scan and download the Archiv-Folder
- removed python2 support
- better error handling (raise Exceptions instead of sys.exit)
- use of `logging` module for debug messages
- [date_from/date_to validation](https://github.com/grindsa/dkb-robo/issues/22)
- additional unittests
- pep8 conformance validation
- unittest coverage measurement via [codecov.io](https://app.codecov.io/gh/grindsa/dkb-robo)

**Bugfixes**:

- ExemptionOrder Link corrected

**Improvements**:

- output of scan_postbox() contains path and filename of the downloaded file

**Improvements**:

- fix release summing-up smaller improvements from last few months

- harmonized workflows
- code-scanning via CodeQL and OSSAR
- modifications due to pylint error messages

**Improvements**:

- pypi packaging added to create_release workflow

**Bugfixes***:

- daf35c9 improved checking account detection (DKB removed the "Cash im Shop" link)
- d40200e0 fix for faulty TAN handling reported in 18

**Bugfixes***:

- 14ba22c7 fix for "Kontoauszugsdownload"