Drop tests on Travis, Appveyor, and Azure Pipelines.

Author: jaraco

.travis.yml

@@ -6,18 +6,13 @@
 
 .. _PyPI link: https://pypi.org/project/skeleton
 
-.. image:: https://dev.azure.com/jaraco/skeleton/_apis/build/status/jaraco.skeleton?branchName=master
-   :target: https://dev.azure.com/jaraco/skeleton/_build/latest?definitionId=1&branchName=master
-
-.. image:: https://img.shields.io/travis/jaraco/skeleton/master.svg
-   :target: https://travis-ci.org/jaraco/skeleton
+.. image:: https://github.com/jaraco/skeleton/workflows/Automated%20Tests/badge.svg
+   :target: https://github.com/jaraco/skeleton/actions?query=workflow%3A%22Automated+Tests%22
+   :alt: Automated Tests
 
 .. image:: https://img.shields.io/badge/code%20style-black-000000.svg
    :target: https://github.com/psf/black
    :alt: Code style: Black
 
-.. .. image:: https://img.shields.io/appveyor/ci/jaraco/skeleton/master.svg
-..    :target: https://ci.appveyor.com/project/jaraco/skeleton/branch/master
-
 .. .. image:: https://readthedocs.org/projects/skeleton/badge/?version=latest
 ..    :target: https://skeleton.readthedocs.io/en/latest/?badge=latest

README.rst

@@ -108,7 +108,7 @@ Relies on a .flake8 file to correct some default behaviors:
 
 ## Continuous Integration
 
-The project is pre-configured to run tests through multiple CI providers.
+The project is pre-configured to run Continuous Integration tests.
 
 ### Github Actions
 
@@ -119,30 +119,6 @@ Features include:
 - run on late (and updated) platform versions
 - automated releases of tagged commits
 
-### Azure Pipelines
-
-[Azure Pipelines](https://azure.microsoft.com/en-us/services/devops/pipelines/) were adopted for free, fast, multi-platform services. See azure-pipelines.yml for more details.
-
-Azure Pipelines require many [complicated setup steps](https://github.com/Azure/azure-devops-cli-extension/issues/968) that have not been readily automated.
-
-Features include:
-
-- test against multiple Python versions
-- run on Ubuntu Bionic
-
-### Travis CI
-
-[Travis CI](https://travis-ci.org) is configured through .travis.yml. Any new project must be enabled either through their web site or with the `travis enable` command.
-
-Features include:
-- test against Python 3
-- run on Ubuntu Bionic
-- correct for broken IPv6
-
-### AppVeyor
-
-A minimal template for running under AppVeyor (Windows) is provided.
-
 ### Continuous Deployments
 
 In addition to running tests, an additional publish stage is configured to automatically release tagged commits to PyPI using [API tokens](https://pypi.org/help/#apitoken). The release process expects an authorized token to be configured with each Github project (or org) `PYPI_TOKEN` [secret](https://docs.github.com/en/free-pro-team@latest/actions/reference/encrypted-secrets). Example: