[appimage] info: displaying 'unknown' when there is no mapped license

CHANGELOG.md

@@ -9,6 +9,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   - new **verified** filter for the management table
 
 ### Improvements
+- AppImage
+  - info window: displaying "unknown" when there is no mapped license
 - Arch
   - adding the AUR's URL on the package information dialog [#339](https://github.com/vinifmor/bauh/issues/339)
 - General

bauh/gems/appimage/controller.py

@@ -480,6 +480,9 @@ class AppImageManager(SoftwareManager, SettingsController):
         if data.get('symlink') and not os.path.islink(data['symlink']):
             del data['symlink']
 
+        if not data.get("license"):
+            data["license"] = self.i18n["unknown"].lower()
+
         return data
 
     def _sort_release(self, rel: tuple):