Update to version 6 of gitleaks

[pburkholder]

Changes proposed in this pull request:

• Add a VERSION to the output for make audit
• Update README on how to run specific tests in bats files
• Added tests for detecting forbidden filenames
• Moved all the regexes exceptions for regex = '''CHANGEME|cha to a final regexes allowlist (support now in v6)
• Changed all the 'whitelists' to 'allowlists'
• Adopted the v6 configuration changes described at: https://github.com/zricethezav/gitleaks/releases/tag/v6.0.0
• Comments why we skip account number test

To test this:

• Run brew upgrade gitleaks and ensure with gitleaks --version you have v6.1.2
  • Note that gitleaks --version with older versions may fail
• run the following:

make patterns
bats development.bats # all should pass
bats caulked.bats  # all should pass
make audit # should pass, unless you're in violation

security considerations

OK. Doesn't weaken any rules, doesn't reveal anything sensitive

[pburkholder]

@ccostino Yeah, something is still wrong. It "should" be a much smaller fix, but we won't know until we have a chance to pair.