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 increased (+1.9%) to 93.125% when pulling 79eeca1 on JuliaTagBot:master into 72e8566 on helgee:master.

[codecov-io]

Codecov Report

Merging #12 into master will increase coverage by 1.87%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #12      +/-   ##
==========================================
+ Coverage   91.76%   93.64%   +1.87%     
==========================================
  Files           4        4              
  Lines         170      173       +3     
==========================================
+ Hits          156      162       +6     
+ Misses         14       11       -3

Impacted Files	Coverage Δ
src/download.jl	100% <0%> (ø)	⬆️
src/backends.jl	86.2% <0%> (+10.34%)	⬆️

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