Fix B907

is manually surrounded by quotes, consider using the conversion flag

Author: bosd

camelot/backends/image_conversion.py

@@ -26,7 +26,7 @@ def __init__(self, backend="poppler", use_fallback=True):
             [description]
         """
         if backend not in BACKENDS.keys():
-            raise ValueError(f"Image conversion backend '{backend}' not supported")
+            raise ValueError(f"Image conversion backend {backend!r} not supported")
 
         self.backend = backend
         self.use_fallback = use_fallback
@@ -62,12 +62,12 @@ def convert(self, pdf_path, png_path):
                         converter.convert(pdf_path, png_path)
                     except Exception as e:
                         raise type(e)(
-                            str(e) + f" with image conversion backend '{fallback}'"
+                            str(e) + f" with image conversion backend {fallback!r}"
                         ).with_traceback(sys.exc_info()[2])
                         continue
                     else:
                         break
             else:
                 raise type(e)(
-                    str(e) + f" with image conversion backend '{self.backend}'"
+                    str(e) + f" with image conversion backend {self.backend!r}"
                 ).with_traceback(sys.exc_info()[2])