Add Turborepo emoji

[Pawka]

Description

Adding emoji for Turborepo. I am not related to the company - just a user.

PR checklist

• [x] The image is 64x64 PNG image
• [x] Image is added to img-buildkite-64 directory
• [x] Image is referenced in img-buildkite-64.json file
• [x] Image is referenced in README markdown file
• [ ] The image can be hosted by Buildkite and made available in Buildkite UI