v2.0.0 Beta - Updated to Jest 27, added deeper implementations for both req and res, refactored and further improved test coverage.

[aboyce]

• Updated to Jest v27
• Updated dependencies
• tmpl from 1.0.4 to 1.0.5 (@dependabot)
• Added in tests for the return type of the res functions (to see if they are chainable or not)
• Updated CI to use new NodeJS versions
• Updated snyk to use new library, removed old
• Improve types for request and response (use library types rather than copying)
• Test structure refactor
  • All request properties have a test for the default value
  • All request properties have a test for when a value is provided
  • All response properties have a test for the default value
  • All response properties have a test for when a value is provided
  • All response functions have a test to check it is chainable, will close #58 if still stale
• Implement changes to resolve #72
• Implement changes to resolve #73

Updated GitHub Action to publish as a beta, updated version number.