Remove Appveyor

It's taking up CI build time, so just remove it.

appveyor.yml

@@ -1,56 +0,0 @@
-image:
- - Ubuntu
- - Visual Studio 2017
-
-environment:
-  CURL_VERSION: 7.56.1
-  CEF_VERSION: 75.1.16+g16a67c4+chromium-75.0.3770.100
-  APPVEYOR_YML_DISABLE_PS_LINUX: true
-  TWITCH-CLIENTID:
-    secure: D3vFGk41HZaJWAZu5slwAHZhB868mGI2aIMS03L2rt4=
-  TWITCH-HASH:
-    secure: IRP5JLwBmPMjA7ADbZu6x2u4thqeEF9HaU1xolhaj74=
-  MIXER-CLIENTID:
-    secure: lQXRRvkeZDVSTUcSaR/kthiKu89K18IubKN913PC0ldjHBQ6sWa8a/t4i1f441N3RPfzAbTrXf2ijRCYYub2Qw==
-  MIXER-HASH:
-    secure: fIxeDxHkiNodwPeNGX+E9tSpyjg/XuT+U9N+jtpT7xU=
-  RESTREAM-CLIENTID:
-    secure: 4KGqX7PbL100GhXWzMFziaHrD/XT9/QKFTGinmPqwOkfRSMMEkUyL998/z3cclUd
-  RESTREAM-HASH:
-    secure: +tu/wCCG3tXnFpjzzXF6zyAOJyt8w48qx47K1bIn/Gs=
-
-install:
-  - git submodule update --init --recursive
-  - cmd: C:\projects\obs-studio\CI\install-qt-win.cmd
-  - cmd: C:\projects\obs-studio\CI\install-script-win.cmd
-  - sh: ./CI/install-dependencies-linux-ubuntu16.sh
-  - sh: ./CI/before-script-linux.sh
-  - sh: ./CI/install-script-linux.sh
-
-build_script:
-  - cmd: call msbuild /m /p:Configuration=%build_config% C:\projects\obs-studio\build32\obs-studio.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
-  - cmd: call msbuild /m /p:Configuration=%build_config% C:\projects\obs-studio\build64\obs-studio.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
-  - sh: cd ./build && make -j4 && cd -
-
-before_deploy:
-  - cmd: C:\projects\obs-studio\CI\before-deploy-win.cmd
-
-deploy_script:
-  - ps: Push-AppveyorArtifact "build.zip" -FileName "$(git describe).zip"
-
-test: off
-
-cache:
-  - dependencies2017.zip
-  - vlc.zip
-  - 'cef_binary_%CEF_VERSION%_windows32_minimal.zip'
-  - 'cef_binary_%CEF_VERSION%_windows64_minimal.zip'
-  - Qt_5.10.1.7z
-
-notifications:
-  - provider: Webhook
-    url:
-      secure: k1kpaz4CB5Rg5a3MTb4XKnd76fJ+9ozz5RACVnNjdgmAjA1OSssZ6LZ3g0NGfzc/
-    headers:
-      Authorization:
-        secure: A0PBwpHtsYzBOuye1EeS0fl562T0NZEInwZp0ZVER1wLQSeE6gzWGrRo2a0E7hii