Remove TruffleBoundary from MarshalModuleBuiltins.LoadsNode#doit.

With a TruffleBoundary the necessary VirtualFrame for releasing the buffer accessed via the `PythonBufferAccessLibrary`
cannot be passed in.

Author: phoeinx

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/MarshalModuleBuiltins.java

@@ -200,7 +200,7 @@ Object doit(VirtualFrame frame, Object file,
     @ArgumentClinic(name = "bytes", conversion = ClinicConversion.ReadableBuffer)
     @GenerateNodeFactory
     abstract static class LoadsNode extends PythonUnaryClinicBuiltinNode {
-        @TruffleBoundary
+
         @Specialization(limit = "3")
         Object doit(VirtualFrame frame, Object buffer,
                         @CachedLibrary("buffer") PythonBufferAccessLibrary bufferLib,