Nextcloud 20 compatibility

[R0Wi]

No description provided.

[codecov]

Codecov Report

Merging #28 into master will increase coverage by 5.04%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master      #28      +/-   ##
============================================
+ Coverage     72.53%   77.57%   +5.04%     
- Complexity      105      111       +6     
============================================
  Files            15       16       +1     
  Lines           324      330       +6     
============================================
+ Hits            235      256      +21     
+ Misses           89       74      -15     

Impacted Files	Coverage Δ	Complexity Δ
lib/AppInfo/Application.php	100.00% <100.00%> (+14.28%)	6.00 <6.00> (+3.00)
lib/BackgroundJobs/ProcessFileJob.php	100.00% <100.00%> (ø)	19.00 <0.00> (ø)
lib/Listener/RegisterFlowOperationsListener.php	100.00% <100.00%> (ø)	3.00 <3.00> (?)
lib/OcrProcessors/OcrProcessorFactory.php	100.00% <100.00%> (ø)	3.00 <1.00> (ø)
lib/Operation.php	100.00% <100.00%> (+27.27%)	18.00 <1.00> (ø)

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[R0Wi]

@bahnwaerter this is ready now. Please check the list at #26 for testing / review purposes.

[bahnwaerter]

I've checked the app with theses changes on a fresh installed NC 20.0.0 instance. The OCR processing with the app works without any issues such that the compatibility for NC 20 is preserved.