remove synk check for every PR update

We are reaching the limit of what we can test and we already have similar
tests in place (`pip-audit` and SonarCloud).

The error we get:

```
You have reached your monthly limit of 200 private tests for your red-hat-ansible-lightspeed-service org.
To learn more about our plans and increase your tests limit visit https://snyk.io/plans.
```