Add app-vulns flag to Snyk scans

[adriangonz]

Beginning January 24th, 2023, Snyk will change the logic for the snyk container test command, also testing application dependencies. More info can be found on the link below:

https://snyk.io/blog/securing-container-applications-using-the-snyk-cli/

To get ahead of that change, we should enable app deps scans in our security pipeline, which can be done by adding the --app-vulns flag to snyk container test.