Remove AppVeyor config (we don't use it anymore for release builds anyway due to codesigning)

appveyor.yml

@@ -1,21 +0,0 @@
---- 
-after_build: 
-  - "set PATH=\"C:\\Program Files (x86)\\Inno Setup 6\";%PATH%"
-  - "cd C:\\projects\\virustotaluploader\\"
-  - "ISCC.exe inno_setup.iss"
-artifacts: 
-  - 
-    name: release_anycpu
-    path: uploader/uploader/build/rel
-  - 
-    name: setup_anycpu
-    path: output
-before_build: 
-  - "cd uploader"
-  - "nuget restore"
-configuration: 
-  - Release
-environment: 
-  APPVEYOR_BUILD_WORKER_IMAGE: "Visual Studio 2019"
-platform: 
-  - "Any CPU"