ci: replace travis with github actions; add dependabot config

[Fdawgs]

No description provided.

[mcollina]

This is still on travis, let's move to github actions first.

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@8ae4105). Click here to learn what that means.
The diff coverage is n/a.

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@@          Coverage Diff          @@
##             master   #3   +/-   ##
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  Coverage          ?    0           
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  Files             ?    0           
  Lines             ?    0           
  Branches          ?    0           
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  Hits              ?    0           
  Misses            ?    0           
  Partials          ?    0           

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