Add github-handle for Lex Roman in heart.md

[daras-cu]

Fixes #6936

What changes did you make?

• In heart.md replaced

- name: Lex Roman

with

- name: Lex Roman
  github-handle: 

Why did you make the changes (we will use this info to test)?

• This change was called for in the issue action items

Screenshots of Proposed Changes Of The Website (if any, please do not screen shot code changes)

No visual changes to the website.

[github-actions]

Want to review this pull request? Take a look at this documentation for a step by step guide!

---

From your project repository, check out a new branch and test the changes.

git checkout -b daras-cu-add-gh-Lex-Roman-6936 gh-pages
git pull https://github.com/daras-cu/website.git add-gh-Lex-Roman-6936

[partapparam]

@daras-cu great job!
The branching was done correctly
You linked the issue.
Code changes were made correctly as stated.
I'm able to confirm in docker that the appearance of the project webpage is unchanged.
Great Job!

[Thinking-Panda]

@daras-cu Thank you for working on this issue. Merge branches are set up correct, code changes are as mentioned in the linked issue and clean. Website also works good on my local machine. Well done!