Update tagbot workflow

[rob-luke]

Update the tagbot workflow to match the latest official documentation recomendation: https://github.com/JuliaRegistries/TagBot#setup

[codecov]

Codecov Report

Merging #70 (3ee9fee) into master (69b9f11) will not change coverage.
The diff coverage is n/a.

❗ Current head 3ee9fee differs from pull request most recent head ff419e7. Consider uploading reports for the commit ff419e7 to get more accurate results

@@           Coverage Diff           @@
##           master      #70   +/-   ##
=======================================
  Coverage   73.68%   73.68%           
=======================================
  Files           6        6           
  Lines         437      437           
=======================================
  Hits          322      322           
  Misses        115      115           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 69b9f11...ff419e7. Read the comment docs.