Average of bin calculated

[isaac-tfn]

The average of distribution bins is now calculated rather than just being the mid point of the bin.

Describe Changes

Task Checklist

• [x] Have unittests been added (testing individual functions and their edge cases)
• [x] Have integration tests been added (if applicable, to test modules of functionality)
• [x] Updated RELEASE.md to reflect changes in PR
• [x] Have new dependencies been added?
  • [x] Have they been added to either requirements.txt or requirements_dev.txt.
  • [x] Have they been added to pyproject.toml

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 92.07%. Comparing base (c70bef4) to head (ed0a619).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #99 +/- ## ========================================== + Coverage 91.99% 92.07% +0.07% ========================================== Files 21 21 Lines 1387 1401 +14 ========================================== + Hits 1276 1290 +14 Misses 111 111 ```

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[isaac-tfn]

@BenTaylor-TfN Updated for weighted average to be an extra column in distribution, and tests updated to pass