Remove deploy configuration

Has been moved to buildkite.

appveyor_deploy.yml

@@ -1,30 +0,0 @@
-clone_depth: 1
-version: '{build}'
-skip_non_tags: true
-image: Visual Studio 2017
-install:
-  - git clone https://github.com/ppy/osu-deploy
-before_build:
-  - ps: if($env:appveyor_repo_tag -eq 'True') { Update-AppveyorBuild -Version $env:appveyor_repo_tag_name }
-  - cmd: git submodule update --init --recursive --depth=5
-  - cmd: nuget restore -verbosity quiet
-build_script:
-  - ps: iex ((New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/appveyor/secure-file/master/install.ps1'))
-  - appveyor DownloadFile https://www.dropbox.com/s/f7hv069mr5tqi2j/deanherbert.pfx.enc?dl=1 # signing certificate
-  - cmd: appveyor-tools\secure-file -decrypt deanherbert.pfx.enc -secret %decode_secret% -out %HOMEPATH%\deanherbert.pfx
-  - appveyor DownloadFile https://puu.sh/A6g75/fdc6f19b04.enc # deploy configuration
-  - cd osu-deploy
-  - nuget restore -verbosity quiet
-  - msbuild osu.Desktop.Deploy.csproj
-  - cmd: ..\appveyor-tools\secure-file -decrypt ..\fdc6f19b04.enc -secret %decode_secret% -out bin\Debug\netcoreapp2.1\osu.Desktop.Deploy.dll.config
-  - dotnet bin/Debug/netcoreapp2.1/osu.Desktop.Deploy.dll %code_signing_password% %APPVEYOR_REPO_TAG_NAME%
-environment:
-  decode_secret:
-    secure: i67IC2xj6DjjxmA6Oj2jing3+MwzLkq6CbGsjfZ7rdY=
-  code_signing_password:
-    secure: 34tLNqvjmmZEi97MLKfrnQ==
-artifacts:
-  - path: 'osu-deploy/releases/*'
-deploy:
-  - provider: Environment
-    name: github