CI: Remove Azure DevOps pipelines (replaced by GitHub Actions)

fixes #1138

.ci/README.md

@@ -2,7 +2,7 @@
 # `.ci`
 
 This directory contains scripts for Continuous Integration platforms. Currently
-Azure Pipelines, but they will also happily run on any Debian-like machine.
+GitHub Actions, but ideally they will also run on any Debian-like machine.
 
 The scripts are usually split into `_install` and `_test` steps. The `_install`
 step will damage your machine, the `_test` step will just run the tests the way

README.md

@@ -1,9 +1,9 @@
 # Mitogen
 
+[![Build Status](https://img.shields.io/github/actions/workflow/status/mitogen-hq/mitogen/tests.yml?branch=master)](https://github.com/mitogen-hq/mitogen/actions?query=branch%3Amaster)
+
 <a href="https://mitogen.networkgenomics.com/">Please see the documentation</a>.
 
 ![](https://i.imgur.com/eBM6LhJ.gif)
 
 [![Total alerts](https://img.shields.io/lgtm/alerts/g/mitogen-hq/mitogen.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/mitogen-hq/mitogen/alerts/)
-
-[![Build Status](https://dev.azure.com/mitogen-hq/mitogen/_apis/build/status/mitogen-hq.mitogen?branchName=master)](https://dev.azure.com/mitogen-hq/mitogen/_build/latest?definitionId=1&branchName=master)

tests/README.md

@@ -7,7 +7,7 @@ started in September 2017. Pull requests in this area are very welcome!
 
 ## Running The Tests
 
-[![Build Status](https://dev.azure.com/mitogen-hq/mitogen/_apis/build/status/mitogen-hq.mitogen?branchName=master)](https://dev.azure.com/mitogen-hq/mitogen/_build/latest?definitionId=1&branchName=master)
+[![Build Status](https://img.shields.io/github/actions/workflow/status/mitogen-hq/mitogen/tests.yml?branch=master)](https://github.com/mitogen-hq/mitogen/actions?query=branch%3Amaster)
 
 Your computer should have an Internet connection, and the ``docker`` command
 line tool should be able to connect to a working Docker daemon (localhost or