Fix CA2200: Re-throwing caught exception changes stack information

[poppastring]

The code in DasBlog.Managers (XmlRpcManager.cs) re-throws a caught exception, which changes stack information and can make debugging harder.

File:

• DasBlog.Web.Repositories\XmlRpcManager.cs (line 140)

Consider using 'throw;' instead of 'throw ex;' to preserve the original stack trace.

Reference: https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca2200