TeXParseError: \widehat and \widetilde

I got an error while using the L"..." macro in Makie.

(Link: https://discourse.julialang.org/t/makie-widehat-and-widetilde-in-xlabel/117277)

```
using MathTeXEngine

generate_tex_elements(L"\widehat{EE}")
```

This code causes a TeXParseError.

```
{
"name": "TeXParseError",
"message": "TeXParseError: unexpected error
at position 2 (string index 2)
$\\widehat{EE}$
^
Stack
[4] TeXExpr :command
└─ \"\\\\widehat\"
[3] TeXExpr :inline_math
[2] TeXExpr :line
[1] TeXExpr :lines

",
"stack": "TeXParseError: unexpected error
at position 2 (string index 2)
$\\widehat{EE}$
^
Stack
[4] TeXExpr :command
└─ \"\\\\widehat\"
[3] TeXExpr :inline_math
[2] TeXExpr :line
[1] TeXExpr :lines

Stacktrace:
[1] texparse(tex::LaTeXStrings.LaTeXString; root::TeXExpr, showdebug::Bool)
@ MathTeXEngine C:\\Users\\lcano\\.julia\\packages\\MathTeXEngine\\4yI25\\src\\parser\\parser.jl:195
[2] texparse
@ C:\\Users\\lcano\\.julia\\packages\\MathTeXEngine\\4yI25\\src\\parser\\parser.jl:113 [inlined]
[3] generate_tex_elements(str::LaTeXStrings.LaTeXString, font_family::MathTeXEngine.FontFamily)
@ MathTeXEngine C:\\Users\\lcano\\.julia\\packages\\MathTeXEngine\\4yI25\\src\\engine\\layout.jl:320
[4] top-level scope
@ c:\\Users\\lcano\\Documents\\test.ipynb:3"
}
```