Remove dependabot yaml

[jgwerner]

Removes dependabot.yaml to rely solely on dependabot configuration options available within the repo's settings.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@a2eeb6a). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #555   +/-   ##
=======================================
  Coverage        ?   75.59%           
=======================================
  Files           ?       15           
  Lines           ?     1008           
  Branches        ?        0           
=======================================
  Hits            ?      762           
  Misses          ?      246           
  Partials        ?        0           

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