Fix deploy conditions in CI script (#1157)

* Fix deploy conditions in CI script

The deploy conditions had been using a powershell-only variable, and not a environment variable. This meant that the deployment failed on both Windows and Linux (expected only on Linux).

* Remove an extra newline

* Remove Debug statements from appveyor build script

appveyor.yml

@@ -83,7 +83,7 @@ deploy:
   symbol_server: https://www.myget.org/F/discord-net/symbols/api/v2/package
   on:
     branch: dev
-    isWindows: True
+    CI_WINDOWS: true
 - provider: NuGet
   server: https://www.myget.org/F/rogueexception/api/v2/package
   api_key:
@@ -91,4 +91,4 @@ deploy:
   symbol_server: https://www.myget.org/F/rogueexception/symbols/api/v2/package
   on:
     branch: dev
-    isWindows: True
+    CI_WINDOWS: true