chore: remove sec-findings.md from PR and ignore it

The audit findings document is intentionally kept out of the mergeable

tree; it can be regenerated locally and is now gitignored.

Author: jkyberneees

.gitignore

@@ -145,6 +145,7 @@ results/
 
 .plan.md
 
+sec-findings.md
 sec-findings.md*.pem
 *.key
 examples/cert.*