Change default tls provider so users won't have to set TLS_PROVIDER explicitly.

src/NzbDrone.Common/Security/SecurityProtocolPolicy.cs

@@ -2,6 +2,7 @@
 using System.Net;
 using NLog;
 using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Common.Extensions;
 using NzbDrone.Common.Instrumentation;
 
 namespace NzbDrone.Common.Security
@@ -18,6 +19,11 @@ namespace NzbDrone.Common.Security
             if (OsInfo.IsNotWindows)
             {
                 // This was never meant to be used on mono, and will cause issues with mono 5 and higher if btls is enabled.
+                // Instead, force TLS provider to legacy for now due to conflict between btls and mediainfo, unless the user explicitly specified it.
+                if (Environment.GetEnvironmentVariable("MONO_TLS_PROVIDER").IsNullOrWhiteSpace())
+                {
+                    Environment.SetEnvironmentVariable("MONO_TLS_PROVIDER", "legacy");
+                }
                 return;
             }