Formatting updates to testing.md

[alexdebrie]

What did you implement:

Added Python syntax highlighting and a bold header for Requirements for Monkeyless Chaos

Todos:

• [X] Have you checked for typos and grammatical errors?
• [ ] If applicable, have you updated the TOC? -- N/A

Is this ready for review?: Yes

[rupakg]

@alexdebrie Thanks.