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

Merging #39 into master will decrease coverage by 1.1%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #39      +/-   ##
==========================================
- Coverage   93.23%   92.12%   -1.11%     
==========================================
  Files          11       11              
  Lines         665      711      +46     
==========================================
+ Hits          620      655      +35     
- Misses         45       56      +11

Impacted Files	Coverage Δ
src/evalpoly.jl	96.77% <0%> (-3.23%)	⬇️
src/evaluation.jl	86.06% <0%> (-2.83%)	⬇️
src/polynomial_system.jl	80.62% <0%> (-2.58%)	⬇️
src/codegen_helpers.jl	98.24% <0%> (-1.76%)	⬇️
src/gradient_codegen.jl	100% <0%> (ø)	⬆️
src/evaluate_codegen.jl	100% <0%> (ø)	⬆️
src/show.jl	98.85% <0%> (+0.01%)	⬆️
src/polynomial.jl	90.47% <0%> (+0.47%)	⬆️
src/helpers.jl	100% <0%> (+3.03%)	⬆️
src/sexponents.jl	77.27% <0%> (+9.09%)	⬆️

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