Install TagBot as a GitHub Action

[JuliaTagBot]

You're receiving this pull request because the now-deprecated Julia TagBot GitHub App is installed for this repository. This pull request installs TagBot as a GitHub Action.
If this PR does not belong in this repository for any reason, feel free to close it.

See this Discourse thread for more details and to ask questions.
Please do not comment on this pull request, because it is unlikely that I (@christopher-dG) will see it.

[coveralls]

Coverage remained the same at 66.846% when pulling 599d6ae on JuliaTagBot:master into 7e08fa4 on gher-ulg:master.

[codecov-io]

Codecov Report

Merging #6 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master      #6   +/-   ##
======================================
  Coverage    70.9%   70.9%           
======================================
  Files          13      13           
  Lines         660     660           
======================================
  Hits          468     468           
  Misses        192     192

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