gnu: python-publicsuffix2: Adjust for Guile 3.0.

* gnu/packages/python-web.scm (python-publicsuffix2): Provide explicit
destination in calls to FORMAT.

gnu/packages/python-web.scm

@@ -2809,7 +2809,7 @@ List.")
              ;; the unused ‘update_psl’ helper command.
              (substitute* "setup.py"
                (("'requests " match)
-                (format "# ~a" match)))
+                (format #f "# ~a" match)))
              #t)))
        #:tests? #f))                  ; the test suite requires network access
     (home-page "https://github.com/pombredanne/python-publicsuffix2")