Implement gherkin linter in GH action

[ernilambar]

Add Gherkin linter

• Add .gherkin-lintrc file
• Exclude this file in distignore and gitattributes
• Add gherkin-lint.yml action config file

[github-actions]

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Co-authored-by: ernilambar <[email protected]>
Co-authored-by: swissspidy <[email protected]>
Co-authored-by: davidperezgar <[email protected]>

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[ernilambar]

I could not find rule to enforce indentation for following:

Then STDOUT should contain:
"""
Success: Checks complete. No errors found.
"""

Generally we write like this:

Then STDOUT should contain:
  """
  Success: Checks complete. No errors found.
  """