Remove old CI config (rust-lang#5572)

* Remove old CI config

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

* Replace outdated badges

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

---------

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

Author: JohnTitor

.editorconfig

@@ -21,6 +21,3 @@ indent_size = unset
 indent_style = unset
 trim_trailing_whitespace = unset
 insert_final_newline = unset
-
-[appveyor.yml]
-end_of_line = unset

.travis.yml

@@ -1,4 +1,4 @@
-# rustfmt [![Build Status](https://travis-ci.com/rust-lang/rustfmt.svg?branch=master)](https://travis-ci.com/rust-lang/rustfmt) [![Build Status](https://ci.appveyor.com/api/projects/status/github/rust-lang/rustfmt?svg=true)](https://ci.appveyor.com/project/rust-lang-libs/rustfmt) [![crates.io](https://img.shields.io/crates/v/rustfmt-nightly.svg)](https://crates.io/crates/rustfmt-nightly) [![Travis Configuration Status](https://img.shields.io/travis/davidalber/rustfmt-travis.svg?label=travis%20example)](https://travis-ci.org/davidalber/rustfmt-travis)
+# rustfmt [![linux](https://github.com/rust-lang/rustfmt/actions/workflows/linux.yml/badge.svg?event=push)](https://github.com/rust-lang/rustfmt/actions/workflows/linux.yml) [![mac](https://github.com/rust-lang/rustfmt/actions/workflows/mac.yml/badge.svg?event=push)](https://github.com/rust-lang/rustfmt/actions/workflows/mac.yml) [![windows](https://github.com/rust-lang/rustfmt/actions/workflows/windows.yml/badge.svg?event=push)](https://github.com/rust-lang/rustfmt/actions/workflows/windows.yml) [![crates.io](https://img.shields.io/crates/v/rustfmt-nightly.svg)](https://crates.io/crates/rustfmt-nightly)
 
 A tool for formatting Rust code according to style guidelines.
 
@@ -7,9 +7,7 @@ If you'd like to help out (and you should, it's a fun project!), see
 Conduct](CODE_OF_CONDUCT.md).
 
 You can use rustfmt in Travis CI builds. We provide a minimal Travis CI
-configuration (see [here](#checking-style-on-a-ci-server)) and verify its status
-using another repository. The status of that repository's build is reported by
-the "travis example" badge above.
+configuration (see [here](#checking-style-on-a-ci-server)).
 
 ## Quick start