Merge branch 'master' into 3.0

# Conflicts:
#	.github/workflows/testing.yml
#	Dockerfile
#	gns3server/version.py

gns3server/controller/symbols.py

@@ -106,8 +106,7 @@ class Symbols:
                         theme = "Custom symbols"
                     symbols.append({"symbol_id": symbol_file, "filename": filename, "builtin": False, "theme": theme})
                     self._symbols_path[symbol_file] = os.path.join(root, filename)
-
-        symbols.sort(key=lambda x: x["filename"])
+        symbols.sort(key=lambda x: x["theme"])
         return symbols
 
     def symbols_path(self):