Proposed changes

Adding OWASP Nettacker to user agents list:
scanners-user-agents.data

See: #4528

PR Checklist

• I have read the CONTRIBUTING doc
• I have added positive tests proving my fix/feature works as intended.
• I have added negative tests that prove my fix/feature considers common cases that might end in false positives
• In case you changed a regular expression, you are not adding a ReDOS for pcre. You can check this using regexploit
• My test use the comment field to write the expected behavior
• I have added documentation for the rule or change (when appropriate)

Further comments

OWASP Nettacker: https://github.com/OWASP/Nettacker
An example of a User-Agent header set by Nettacker is: User-Agent: Nettacker 0.4.0 QUIN

For the reviewer

• Positive and negative tests were added
• Tests cover the intended fix/feature properly
• No usage of dangerous constructs like ctl:requestBodyAccess=Off were used in the rule
• In case a regular expression was changed, there is no ReDOS
• Documentation is clear for the rule/change