fix: replacing method used for displaying messages

[37IulianPopovici]

Maintaining same functionality as https://github.com/snyk/snyk-nuget-plugin/pull/217 but makes the code more readable (we're not erroring out, just displaying a warn message for the user)

[snyksec]

:tada: This issue has been resolved in version 2.7.6 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: