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.

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@2ea7d6e). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master       #3   +/-   ##
=========================================
  Coverage          ?   89.18%           
=========================================
  Files             ?        1           
  Lines             ?      379           
  Branches          ?        0           
=========================================
  Hits              ?      338           
  Misses            ?       41           
  Partials          ?        0           

Impacted Files	Coverage Δ
src/FlexibleArrays.jl	89.18% <0.00%> (ø)

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