Reword audit prompt message for clarity

The old audit prompt message was confusing in the case of a false positive. This new wording suits both genuine findings and false positives.

Fixes #734

detect_secrets/audit/io.py

@@ -130,7 +130,7 @@ def __init__(self, allow_labelling: bool, allow_backstep: bool) -> None:
 
     def __str__(self) -> str:
         if 'Y' in self.valid_input:
-            output = 'Is this a secret that should be committed to this repository?'
+            output = 'Should this be committed to the repository?'
         else:
             output = 'What would you like to do?'