Fix/truffle hog ci (#10)

* ci: fix TruffleHog base/head commit comparison

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Co-authored-by: Hernan Monserrat <16483541+hemonserrat@users.noreply.github.com>

Author: hemonserrat

.github/workflows/security.yml

@@ -88,8 +88,8 @@ jobs:
       uses: trufflesecurity/trufflehog@main
       with:
         path: ./
-        base: main
-        head: HEAD
+        base: ${{ github.event_name == 'pull_request' && github.event.pull_request.base.sha || 'HEAD~1' }}
+        head: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || 'HEAD' }}
         extra_args: --debug --only-verified
 
   crypto-analysis: