Fix nullability errors in MediaBrowser.Model

MediaBrowser.Model/Entities/ProviderIdsExtensions.cs

@@ -48,7 +48,7 @@ namespace MediaBrowser.Model.Entities
                 return null;
             }
 
-            instance.ProviderIds.TryGetValue(name, out string id);
+            instance.ProviderIds.TryGetValue(name, out string? id);
             return id;
         }
 

MediaBrowser.Model/Net/MimeTypes.cs

@@ -177,7 +177,7 @@ namespace MediaBrowser.Model.Net
 
             var ext = Path.GetExtension(path);
 
-            if (_mimeTypeLookup.TryGetValue(ext, out string result))
+            if (_mimeTypeLookup.TryGetValue(ext, out string? result))
             {
                 return result;
             }