remove appveyor CI

extra/appveyor/appveyor.yml

@@ -1,53 +0,0 @@
-version: 12.0.{build}
-
-image: Visual Studio 2019
-
-shallow_clone: true
-
-environment:
-  matrix:
-    - PLATFORM: x86
-      VCVARSALL_PLATFORM: x86
-      GENERATOR: "Visual Studio 16 2019"
-      VSARCH: "Win32"
-    - PLATFORM: x64
-      VCVARSALL_PLATFORM: x86_amd64
-      GENERATOR: "Visual Studio 16 2019"
-      VSARCH: "x64"
-
-init:
-# Make VS 2019 command line tools available
-- call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat" %VCVARSALL_PLATFORM%
-
-install:
-# We need to install NSIS to create the packaged installer executable.
-- choco install nsis-unicode -y
-
-# Move all woking directory items except `appveyor.yml` to `love` subdirectory.
-- md love
-- for /D %%i in (*) do @if "%%i" NEQ "love" @move %%i love\%%i
-- for %%i in (*) do @if "%%i" NEQ "appveyor.yml" @move %%i love\%%i
-# clone megasource and move into top directory.
-- git clone --depth 1 --single-branch --branch 12.x https://github.com/love2d/megasource.git megasource
-- cd megasource
-- for /D %%i in (*) do @move %%i ..\%%i
-- for %%i in (*) do @move %%i ..\%%i
-- cd ..
-# move love source to megasource's libs\love.
-- move love libs\love
-
-before_build:
-- cmake -G "%GENERATOR%" -A "%VSARCH%" -H. -Bbuild
-
-build_script:
-- cmake --build build --target PACKAGE --config Release
-
-after_build:
-
-before_test:
-
-test_script:
-
-artifacts:
-- path: build\*.zip
-- path: build\*.exe