Secret scanning matches on entire line instead of matching on any part of a line

Issue Summary

Secret scanning matches on entire line instead of matching on any part of a line

Steps to Reproduce

1. Push a secret that is wrapped by other characters e.g.:

   text before 'Basic TA6QW9uT25lRGV2b3BzQTA6QW9uT25lRGV2b3BzQ==' text after

Expected Results

Secret is detected and users are notified

Actual Results

The secret is not picked up and there are no notifications 

Workaround

Add `.*` to the secret line pattern rule e.g. 

 .*(\"|')?Basic ([A-Za-z0-9\\+=]{44}(\"|'))?.*