Strikethrough does not work in code blocks

[JHaller27]

Strikethroughs in code blocks formatted with strikethrough (rather than displaying bare symbols).

Example:

Code	Expected	Actual	Comment
~~text~~	~~text~~	~~text~~	Good so far
`~~text~~`	~~text~~	~~text~~	Strikethrough should not display
`**text**`	**text**	**text**	For example, bold works as expected

[SyntaxRules]

I pulled up the showdown editor and confirmed that this is not an issue in the latest showdown.js. That means its likely that upgrading the showdown.js dependency in package.json will fix this issue.

If you care to speed up the process, could you check that upgrading the showdown version solves this issue for you? In any regard, I'll release a new version: 1.2.0 soon and check it there.