community/font-manager: upgrade to 0.9.0
https://github.com/FontManager/font-manager/releases/tag/0.9.0
https://github.com/FontManager/font-manager/releases/tag/0.8.9
0.8.9 resolves compile errors with Vala that led to rebuild failure on a 3.21 builder (error log).
The application identifier was changed in 0.9.0, so asset filenames in font_viewer()
were updated accordingly.
Edited by mio