Render error when single quotation mark meets right curvly bracket

A single example like this will cause a render error ( tested on Release 1.3.1)
```c++
void minimum_example() {

jinja2::Template tpl;

tpl.Load("{{ 'Hello World!' + '\n'}}");

std::cout << tpl.RenderAsString({}).value() << std::endl;

}
```
I found the issue could be avoided if a space is inserted:
```c++
tpl.Load("{{ 'Hello World!' + '\n' }}");
```

But considering template file is usually not so space sensitive and accurate, I wonder if this is something that can be fixed?