Remove api key per security policy

appveyor.yml

@@ -75,8 +75,6 @@ deploy:
 
   - provider: NuGet                             # deploy to MyGet.org
     server: https://www.myget.org/F/mobiusforspark/api/v2/package
-    api_key:
-      secure: 1c6+PZ3zOdIgIy2y8rf1g/NfbcfoxwNcymNBUr1591mD3Ull2X32Qvw2QyCXqFka
     skip_symbols: false
     symbol_server: https://www.myget.org/F/mobiusforspark/api/v2/package
     artifact: /Microsoft.*\.nupkg/