appveyor: Do not fail build on nuget conflict

It will also not fail on any error to push, but
since this is a temporary workaround this is better.

Author: angularsen

appveyor.yml

@@ -41,4 +41,4 @@ deploy:
     branch: master
 deploy_script:
   - appveyor DownloadFile https://dist.nuget.org/win-x86-commandline/latest/nuget.exe  
-  - ps: ($artifacts.values | Where-Object {($_.path -like '*.nupkg') -and  !($_.path -like '*.symbols.nupkg')}) | foreach-object {nuget.exe push $_.path -Source https://www.nuget.org/api/v2/package -ApiKey $env:api_key; if ($lastexitcode -ne 0) {throw}}
+  - ps: ($artifacts.values | Where-Object {($_.path -like '*.nupkg') -and  !($_.path -like '*.symbols.nupkg')}) | foreach-object {nuget.exe push $_.path -Source https://www.nuget.org/api/v2/package -ApiKey $env:api_key}