Fix escaping in julia-in-string docstring

[ronisbr]

Hi!

Before this commit, the docstring of julia-in-string was rendered as:

After, it is rendered as:

This commit also suppresses a warning in Emacs 29 related to unescaped ':

NEWS from Emacs 29

*** Byte compilation will now warn about some quoting mistakes in docstrings.
When writing code snippets that contains the "'" character (APOSTROPHE),
that quote character has to be escaped to avoid Emacs displaying it as
"’" (LEFT SINGLE QUOTATION MARK), which would make code examples like>

(setq foo '(1 2 3))

invalid. Emacs will now warn during byte compilation if it seems
something like that, and also warn about when using RIGHT/LEFT SINGLE
QUOTATION MARK directly. In both these cases, if these characters
should really be present in the docstring, they should be quoted with
"=".

Closes #180

[ronisbr]

I am pretty sure the errors are not related with this commit.

[ronisbr]

Bump! :)

[tpapp]

Thanks!

[ronisbr]

Thanks!