fix: for emphasis, include the case where the end of the content string is an escape sequence

[stevenxxiu]

Checklist

• Used only camelCase variable names.
• If functionality is added or modified, also made respective changes to the readme.
• Used conventional commits keywords.

Some cases I missed yesterday:

abc *\*t* def
abc _\_t_ def
abc ~~\~t~~ def
abc ==\=t== def

abc *t\** def
abc _t\__ def
abc ~~t\~~~ def
abc ==t\=== def

abc *\** def
abc __\___ def
abc ~~\~~~ def
abc ==\=== def

*\** def
__\___ def
~~\~~~
==\===

It'll be a lot easier to code this if Lua had proper eregex! Or maybe I can just use Treesitter instead and figure out how to find the nearest scopes.

[chrisgrieser]

Thx