remove single quotes in some logging messages (#4908)

('FileNotFoundError: [Errno 2] No such file or directory: ''')
->
(FileNotFoundError: [Errno 2] No such file or directory: '')

gallery_dl/postprocessor/common.py

@@ -41,7 +41,7 @@ class PostProcessor():
                     "_archive_" + self.name)
             except Exception as exc:
                 self.log.warning(
-                    "Failed to open %s archive at '%s' ('%s: %s')",
+                    "Failed to open %s archive at '%s' (%s: %s)",
                     self.name, archive, exc.__class__.__name__, exc)
             else:
                 self.log.debug("Using %s archive '%s'", self.name, archive)