Remove AppVeyor CI config and badge from README

Co-authored-by: syoyo <18676+syoyo@users.noreply.github.com>

README.md

@@ -26,8 +26,6 @@ Currently TinyGLTF is stable and maintenance mode. No drastic changes and featur
 
 ## Builds
 
-[![Build status](https://ci.appveyor.com/api/projects/status/warngenu9wjjhlm8?svg=true)](https://ci.appveyor.com/project/syoyo/tinygltf)
-
 ![C/C++ CI](https://github.com/syoyo/tinygltf/workflows/C/C++%20CI/badge.svg)
 
 ## Features

appveyor.yml

@@ -1,18 +0,0 @@
-version: 0.9.{build}
-
-image:
-  - Visual Studio 2015
-
-# scripts that runs after repo cloning.
-install:
-  - vcsetup.bat
-
-platform: x64
-configuration: Release
-
-build:
-  parallel: true
-  project: TinyGLTFSolution.sln
-
-after_build:
-  - examples.bat