Changed release version to be 0.4.0

[ronanstokes-db]

Proposed changes

Changed release version to be 0.4.0

Minimum spark version used in builds and tests is pyspark 3.2.1

Types of changes

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• Bug fix (non-breaking change which fixes an issue)
• [] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
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• Non code change (readme, images or other non-code assets)
• Documentation Update (if none of the other choices apply)

Checklist

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.87%. Comparing base (4206b5c) to head (cddba97).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #271   +/-   ##
=======================================
  Coverage   92.87%   92.87%           
=======================================
  Files          42       42           
  Lines        3577     3577           
  Branches      631      631           
=======================================
  Hits         3322     3322           
  Misses        145      145           
  Partials      110      110           

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