Fix character escaping (')

[dv]

Seems like this inky-rb suffers from a bug that inky suffered from too: foundation/inky#57

It looks bad in Outlook.

[joeworkman]

This repository is being sunset. The Inky project is being rewritten in Rust with a single canonical core and official bindings for all major languages — including a new Ruby gem that uses the shared Rust core via FFI (fiddle).

This means:

• One implementation, identical output across all languages
• No more Ruby-specific bugs or maintenance burden
• The new Ruby gem will have zero gem dependencies (fiddle is in Ruby's stdlib)

You can follow progress at https://github.com/foundation/inky.

Thanks for using inky-rb!