Update aspect-build emoji to brand color

[gregmagolan]

Description

Brand color of this icon was off when first added. This fixes that.

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
• [x] The image can be hosted by Buildkite and made available in Buildkite UI

[gregmagolan]

@jfhinchcliffe This is ready to land. This emoji is already previously added. This PR just updates the image to fixup the color.