Add GitHub Action for updating license file for dependabot branches

[kathy-t]

Description
This PR adds a GitHub action that is triggered on a push event for branches that begin with dependabot/, updates the license file, and pushes the changes if there are any.

From dependabot docs:

Dependabot generates a branch for each pull request. Each branch name includes dependabot, and the package manager and dependency that are updated. By default, these parts are separated by a / symbol, for example: dependabot/npm_and_yarn/next_js/acorn-6.4.1.

If you happen to create a branch that starts with dependabot/ then this action will run, but it's probably unlikely to happen since we use hubflow.

A git name and email has to be set in order to commit something. I used option 2 in this comment to display that the user who performed the commit is the GitHub Action bot.

An example of this GitHub action running is in this draft PR: #1516.

• Note the actual commit that was done by the GitHub action.
• You can view the actual GitHub action job here.

Issue
SEAB-4223

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[denis-yuen]

very cool time saver, better than my idea 😄

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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[codecov]

Codecov Report

Merging #1517 (dc0c220) into develop (19001e8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #1517   +/-   ##
========================================
  Coverage    43.88%   43.88%           
========================================
  Files          312      312           
  Lines         9380     9380           
  Branches      2244     2244           
========================================
  Hits          4116     4116           
  Misses        3433     3433           
  Partials      1831     1831           

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[coverbeck]

Neat, I did not know you could do that.

[david4096]

Nice one!