Avoid running security audit on forked repos

[juarezr]

This is a minor caveat from using a scheduled action for running the security audit.

This adds a condition for skipping the security audit action/workflow on forked GitHub repositories for avoiding polluting logs and notifications.

[coveralls]

Pull Request Test Coverage Report for Build 719537026

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 78.404%

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Totals
Change from base Build 645813472:	0.0%
Covered Lines:	2476
Relevant Lines:	3158

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💛 - Coveralls