Support for multiple chat downloads and autorefresh

[Hugeldugelking]

The script is now able to download media from multiple chats and scan the chats again after a given interval. For this, the config.yaml needed some modifications. Tests were also updated for the modified downloader script.

fixes: #77

[Dineshkarthik]

@Hugeldugelking please check the Pylint errors. More details can be found here

[Hugeldugelking]

@Dineshkarthik I don't get no pylint errors anymore. Sorry, it's my first time working on an open project with such tools :)

[codecov]

Codecov Report

Merging #235 (e7f3ed9) into master (92fb58a) will increase coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #235      +/-   ##
==========================================
+ Coverage   98.93%   99.06%   +0.13%     
==========================================
  Files           6        6              
  Lines         187      213      +26     
==========================================
+ Hits          185      211      +26     
  Misses          2        2              

Impacted Files	Coverage Δ
media_downloader.py	98.64% <100.00%> (+0.28%)	⬆️

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[Dineshkarthik]

@Hugeldugelking is the auto_refresh optional or mandatory? I don't want to make this application something like long-pooling/continuous running one, it should be a stateful (last read message ids) single run and the users can add it to cron if they want to run this on regular intervals.

[Hugeldugelking]

@Dineshkarthik auto_refresh is optional. If set to 0 the script will only run once. I did this because I want to try to put this script in a docker container to run it on an unraid server for example. Your Idea with cron is great and I will take a look at it.
Should auto_refresh remain optional in the application? Otherwise I'd remove this from the code.
Regarding the failing checks: This has nothing to do with my modification, does it?

[ofifoto]

bump :3