remove some unused filters

app/__init__.py

@@ -367,13 +367,6 @@ def create_app():
     def cachebust(subject):
         return f'{subject}?v={str(int(time.time()))}'
 
-    @app.template_filter('theme_name')
-    def get_theme_name(subject: str):
-        if subject == 'style':
-            return 'Default'
-
-        return f'{subject.removeprefix('theme-').replace('-', ' ').capitalize()} (beta)'
-
     @app.template_filter('fromjson')
     def fromjson(subject: str):
         return json.loads(subject)