Fix Content-Type in FileList fixture

Author: mynameisbogdan

src/NzbDrone.Core.Test/IndexerTests/FileListTests/FileListFixture.cs

@@ -33,7 +33,7 @@ public async Task should_parse_recent_feed_from_FileList()
 
             Mocker.GetMock<IHttpClient>()
                 .Setup(o => o.ExecuteAsync(It.Is<HttpRequest>(v => v.Method == HttpMethod.Get)))
-                .Returns<HttpRequest>(r => Task.FromResult(new HttpResponse(r, new HttpHeader(), recentFeed)));
+                .Returns<HttpRequest>(r => Task.FromResult(new HttpResponse(r, new HttpHeader { { "Content-Type", "application/json" } }, recentFeed)));
 
             var releases = await Subject.FetchRecent();