ci: Enable Dependabot version updates for GitHub Actions

[matthewfeickert]

• Add GitHub Dependabot config to check for GitHub Action version updates and to open PRs if available. Set the check and update interval to weekly.
  • c.f. https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot

[codecov]

Codecov Report

Base: 85.71% // Head: 85.71% // No change to project coverage 👍

Coverage data is based on head (3f24e64) compared to base (e04193b).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #153   +/-   ##
=======================================
  Coverage   85.71%   85.71%           
=======================================
  Files           2        2           
  Lines         217      217           
  Branches       57       57           
=======================================
  Hits          186      186           
  Misses         27       27           
  Partials        4        4           

Flag	Coverage Δ
unittests-3.10	85.25% <ø> (ø)
unittests-3.6	83.96% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[eduardo-rodrigues]

Good to have this. Had not realised it was not in. I have it for my other packages and it is very useful. I set the interval to "monthly" but up to you.