Backend.Tests: yet another ex marshalling tweak

After trying this better hack[1] to emulate macOS&windows build
agents without 'dotnet' (v6), master branch of geewallet started
complaining about this marshalling difference, which again we
don't care about, so we tweak it to stop complaining.

[1] nblockchain/fsx@b33db81

src/GWallet.Backend.Tests/MarshallingData.fs

@@ -113,7 +113,9 @@ module MarshallingData =
                     let tweakedEndOfStackTrace =
                         endOfStackTrace
                             .Replace(":line 42", ":41 ")
+                            .Replace(":line 41", ":41 ")
                             .Replace(":line 65", ":64 ")
+                            .Replace(":line 64", ":64 ")
                     stackTraceJToken.Replace (tweakedEndOfStackTrace |> JToken.op_Implicit)
 
                 let binaryFormToken = jsonEx.SelectToken fullBinaryFormPath