Use GitHub Actions for continuous integration

[per1234]

On every push, pull request, and periodically, use the codespell-project/actions-codespell action to check for commonly misspelled words.

In the event of a false positive, the problematic word should be added, in all lowercase, to the ignore-words-list field of ./.codespellrc. Regardless of the case of the word in the false positive, it must be in all lowercase in the ignore list. The ignore list is comma-separated with no spaces.

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On every push or pull request that affects library source or example files, use the arduino/compile-sketches action to compile all example sketches for the specified boards.

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On creation or commit to a pull request, use the arduino/report-size-deltas action to comment a report of the resulting change in memory usage of the examples to the PR thread.

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On every push or pull request, run Arduino Lint to check for common problems not related to the project code.

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Fixes https://github.com/arduino-libraries/ArduinoECCX08/issues/28

[per1234]

You can see the CI runs in my fork here: https://github.com/per1234/ArduinoECCX08/actions?query=branch%3Aci