Fix imgconverter: Failed to extract translation messages

Author: tk0miya

sphinx/ext/imgconverter.py

@@ -31,12 +31,12 @@ def is_available(self) -> bool:
             return True
         except OSError as exc:
             logger.warning(__(
-                f"Unable to run the image conversion command {self.config.image_converter!r}. "
+                "Unable to run the image conversion command %r. "
                 "'sphinx.ext.imgconverter' requires ImageMagick by default. "
                 "Ensure it is installed, or set the 'image_converter' option "
                 "to a custom conversion command.\n\n"
-                f'Traceback: {exc}'
-            ))
+                "Traceback: %s"
+            ), self.config.image_converter, exc)
             return False
         except CalledProcessError as exc:
             logger.warning(__('convert exited with error:\n'