PR #58: Fix colab exec printing raw IPython repr instead of actual HTML content

[merlinran]

Hi maintainers — I ran into an issue where colab exec prints <IPython.core.display.HTML object> instead of the actual content when a notebook cell produces rich HTML output.

Root cause: When a kernel sends display_data with both text/html (the real content) and text/plain (the Python repr), all three display_output paths only look for text/plain and print the useless repr.

Fix in PR #58: Adds a text/html branch before the text/plain fallback, using html.parser.HTMLParser to strip tags for terminal display. The result isn't a full HTML renderer, but it surfaces the actual text content — a clear improvement over the current behavior.

PR: #58

I'm aware that you "aren't accepting external contributions at this time.". Adding it just for the benefit of others.