Fixes an issue with certain reports

[adracea]

Uploading a burp suite report that contained certain characters ended up with throwing errors due to the str(self.description) which would end up with a partial report upload .
For example the "Interesting input handling: Magic value: null" issue generated by the Burp Pro Plugin Backslash Powered Scanner ended up not uploading due to the fact that it contained a multi-line table .

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• Your code is flake8 compliant (DefectDojo's code isn't currently flake8 compliant, but we're trying to correct that.)
• If this is a new feature and not a bug fix, you've included the proper documentation in the ReadTheDocs documentation folder. https://github.com/DefectDojo/Documentation/tree/master/docs or provide feature documentation in the PR.
• Add applicable tests to the unit tests.