Minor fix for "M-x pdb"

* lisp/progmodes/gud.el (gud-pdb-marker-regexp): Add @ and SPC to
the regexp.  (Bug#30208)

lisp/progmodes/gud.el

@@ -1605,7 +1605,7 @@ and source-file directory for your debugger."
 ;; Last group is for return value, e.g. "> test.py(2)foo()->None"
 ;; Either file or function name may be omitted: "> <string>(0)?()"
 (defvar gud-pdb-marker-regexp
-  "^> \\([-a-zA-Z0-9_/.:\\]*\\|<string>\\)(\\([0-9]+\\))\\([a-zA-Z0-9_]*\\|\\?\\|<module>\\)()\\(->[^\n\r]*\\)?[\n\r]")
+  "^> \\([-a-zA-Z0-9_/.:@ \\]*\\|<string>\\)(\\([0-9]+\\))\\([a-zA-Z0-9_]*\\|\\?\\|<module>\\)()\\(->[^\n\r]*\\)?[\n\r]")
 
 (defvar gud-pdb-marker-regexp-file-group 1)
 (defvar gud-pdb-marker-regexp-line-group 2)