Merge branch 'waywardmonkeys/update-ci' (#350)

* waywardmonkeys/update-ci:
  ci: Remove appveyor config and build status badges.
  ci: Update to `actions/checkout@v3`.

.github/workflows/rust.yml

@@ -35,7 +35,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           fetch-depth: 1
       - name: Install Rust

proptest/README.md

@@ -1,7 +1,6 @@
 # Proptest
 
 [![Build Status](https://github.com/proptest-rs/proptest/workflows/Rust/badge.svg?branch=master)](https://github.com/proptest-rs/proptest/actions)
-[![Build status](https://ci.appveyor.com/api/projects/status/ofe98xfthbx1m608/branch/master?svg=true)](https://ci.appveyor.com/project/AltSysrq/proptest/branch/master)
 [![](https://img.shields.io/crates/v/proptest.svg)](https://crates.io/crates/proptest)
 [![](https://img.shields.io/website/https/proptest-rs.github.io/proptest.svg)][book]
 [![](https://docs.rs/proptest/badge.svg)][api-docs]

proptest/readme-prologue.md

@@ -1,7 +1,6 @@
 # Proptest
 
 [![Build Status](https://github.com/proptest-rs/proptest/workflows/Rust/badge.svg?branch=master)](https://github.com/proptest-rs/proptest/actions)
-[![Build status](https://ci.appveyor.com/api/projects/status/ofe98xfthbx1m608/branch/master?svg=true)](https://ci.appveyor.com/project/AltSysrq/proptest/branch/master)
 [![](https://img.shields.io/crates/v/proptest.svg)](https://crates.io/crates/proptest)
 [![](https://img.shields.io/website/https/proptest-rs.github.io/proptest.svg)][book]
 [![](https://docs.rs/proptest/badge.svg)][api-docs]