capture exit code for sarif

[dani-santos-code]

Description

When running kubeaudit on the cli, we generally yield an exit code other than 0 if the report contains errors.

However, when we run it with the sarif format, we get 0 even when we have errors. This happens, because we're returning
here to avoid printing extra info to the console. This means we never reach this line.

Fixes #575

Type of change

• Bug fix 🐛
• New feature ✨
• This change requires a documentation update 📖
• Breaking changes ⚠️

How Has This Been Tested?

• Test A

1. use one of the manifest files in the repo to test. Example: auditors/privileged/fixtures/privileged-nil.yml

2. go run ./cmd/main.go all -f auditors/privileged/fixtures/privileged-nil.yml --format=sarif

3. when you run echo $? you should see 2

Checklist:

• I have 🎩 my changes (A 🎩 specifically includes pulling down changes, setting them up, and manually testing the changed features and potential side effects to make sure nothing is broken)
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• The test coverage did not decrease
• I have signed the appropriate Contributor License Agreement

[clintonShopify]

LGTM