Update Secret Detection .gitleaks.toml to include `keywords` and updated regexes

Proposal

We should take advantage of some of the new configuration features in the latest version of gitleaks, namely leveraging rule keywords.

If a rule has a keywords present then gitleaks will perform a string compare operation to determine if a region of code likely contains a secret for the current rule. This speeds up gitleaks scans significantly.

Tasks

• Update the Secret Detection analyzer's gitleaks.toml file to include keywords