Add contributing and code of conduct, update dependencies

[codecov-commenter]

Codecov Report

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

Project coverage is 99.72%. Comparing base (8143cb9) to head (6edfefa).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #74 +/- ## ======================================= Coverage 99.72% 99.72% ======================================= Files 6 6 Lines 718 718 Branches 164 164 ======================================= Hits 716 716 Misses 1 1 Partials 1 1 ```

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