CI maintenance

[visr]

I'm going to launch off some automated PRs against the JuliaGeo packages, using this script: https://github.com/julia-actions/MassInstallAction.jl/tree/master/demos/MaintenanceDec2020

This will do 3 commits, in case they are not yet done:

• Set up TagBot workflow (or doing the required update of TagBot)
• Build docs on GitHub Actions (when they exist)
• Switch to GitHub Actions for CI, removing the Travis and Appveyor configuration files

GitHub Actions offers Mac, Linux and Windows. The reason to get off Travis CI is because we ran out of the free credits that Travis CI introduced recently. And since GitHub Actions also supports Windows, Appveyor is removed to keep it all in one place. If you prefer to retain Appveyor, or have any other comments, let me know here or on one of the PRs.

[visr]

Since the TagBot updates are straightforward, I merged those already.

These I'll leave open for comments for a few days:

Build docs on GitHub Actions

• MassInstallAction: Install the Documenter workflow on this repository GeoDatasets.jl#12
• MassInstallAction: Install the Documenter workflow on this repository CFTime.jl#10
• MassInstallAction: Install the Documenter workflow on this repository NetCDF.jl#133
• MassInstallAction: Install the Documenter workflow on this repository GeoFormatTypes.jl#9
• MassInstallAction: Install the Documenter workflow on this repository GADM.jl#35
• MassInstallAction: Install the Documenter workflow on this repository GeoJSON.jl#28

Switch to GitHub Actions for CI, removing the Travis and Appveyor configuration files

• MassInstallAction: Install the CI workflow on this repository GeoInterface.jl#37
• MassInstallAction: Install the CI workflow on this repository CFTime.jl#11
• MassInstallAction: Install the CI workflow on this repository NetCDF.jl#134
• MassInstallAction: Install the CI workflow on this repository LibGEOS.jl#80
• MassInstallAction: Install the CI workflow on this repository Proj.jl#46
• MassInstallAction: Install the CI workflow on this repository LibSpatialIndex.jl#12
• MassInstallAction: Install the CI workflow on this repository GDAL.jl#107
• MassInstallAction: Install the CI workflow on this repository GeoFormatTypes.jl#10
• MassInstallAction: Install the CI workflow on this repository GADM.jl#36
• MassInstallAction: Install the CI workflow on this repository GeoJSON.jl#29

[visr]

Closing since all linked pull requests are now merged. I also went ahead and removed the webhooks of the CI services we don't use anymore, and updated the CI badges in the READMEs.