4.9.0:
* added 60+ icons and fixed many filters
* new in app icon search, thx to @donnnno
* further improved CI
* improved contribution guideline

Thx to an active contributing community (in alphabetical order): @bdju, @benoit.harrault, @deusdenton, @egecelikci, @germe-fur, Jochen Spickhof, @load_sas, @twilight1794, @zachir
