Using latest pipeline from GitHub fixes :tt bug.

The README for `jch/html-pipeline` states that the EmojiFilter does NOT
interpret emoji enclosed within `<pre>`, `<code>` or `<tt>` tag pairs.
The current released Gem on RubyGems, contrary to doc, ignores `<tt>`.
Current GitHub commit works as documented.

RSpec: 703 examples, 0 failures
RuboCop: 179 files inspected, no offenses detected