Drop ubuntu 18.04, move to latest

[lazyoracle]

What

Drop ubuntu 18.04, move to latest

Why

Closes #203

Checklist

Please include and complete the following checklist. Your Pull Request is (in most cases) not ready for review until the following have been completed. You can create a draft PR while you are still completing the checklist. Check the Contribution Guidelines for more details. You can mark an item as complete with the - [x] prefix

• [ ] Tests - Added unit tests for new code, regression tests for bugs and updated the integration tests if required
• [ ] Formatting & Linting - black and flake8 have been used to ensure styling guidelines are met
• [ ] Type Annotations - All new code has been type annotated in the function signatures using type hints
• [ ] Docstrings - Docstrings have been provided for functions in the numpydoc style
• [ ] Documentation - The tutorial style documentation has been updated to explain changes & new features
• [ ] Notebooks - Example notebooks have been updated to incorporate changes and new features
• [ ] Changelog - A short note on this PR has been added to the Upcoming Release section

[codecov[bot]]

Codecov Report

Merging #204 (ed37440) into dev (f727420) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #204   +/-   ##
=======================================
  Coverage   74.12%   74.12%           
=======================================
  Files          38       38           
  Lines        5588     5588           
=======================================
  Hits         4142     4142           
  Misses       1446     1446           

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