Add the option to specify which format you want to output, defaulting to sarif.

[williamfalconeruk]

Add the option to change the output of the report from the gitleaks scan. I think it's useful to have SARIF as the default, as Github actions can upload this for code scanning. please see PR #34 for a proposed solution.

[zricethezav]

The reports default to sarif in v2 of this action.

Leaving this issue open to consider adding an option to specify the format of the report