fix: prefer fingerprint to fingerprints to match other flags

[elsapet]

Description

Fix to follow convention of other list flags e.g. skip-rule, only-rule, skip-path we change exclude-fingerprints to exclude-fingerprint (single). We keep the exclude terminology since we are not skipping anything here (that is, the findings are still "found"); we are simply excluding them from showing up in the report

Checklist

• I've added test coverage that shows my fix or feature works as expected.
• I've updated or added documentation if required.
• I've included usage information in the description if CLI behavior was updated or added.
• PR title follows Conventional Commits format