fix: fix comment on unmonitored project with no vulns

[mathild3r]

• [x] Tests written and linted ℹ︎
• [x] Documentation written ℹ︎
• [x] Commit history is tidy ℹ︎

What this does

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Snyk delta send empty array when there is no vuls, adding a length check to comment the project only if there are vuln.

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[aarlaud]

:tada: This PR is included in version 2.0.8 :tada:

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