Update to Documenter 1 and update CompatHelper

[devmotion]

The PR updates the makedocs call in docs/make.jl to Documenter 1 and removes the keyword arguments that were removed in Documenter 1. To avoid such issues with breaking changes in the future, I also added compat entries to docs/Project.toml, as suggested by the Documenter docs, and enabled CompatHelper for the docs environment. I used the opportunity to update the CompatHelper action with the template in the CompatHelper repo.

Should fix the docs build failure in #58.

[codecov]

Codecov Report

Merging #59 (c5fffa7) into master (f16fa63) will decrease coverage by 0.87%.
Report is 5 commits behind head on master.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #59      +/-   ##
==========================================
- Coverage   98.32%   97.45%   -0.87%     
==========================================
  Files           8        9       +1     
  Lines         538      551      +13     
==========================================
+ Hits          529      537       +8     
- Misses          9       14       +5     

see 3 files with indirect coverage changes

[hexaeder]

Thanks again! I'll have a look at the new docs once they are built on master and tag the new version afterward.