[Bug]: Image Thumbnails for "Run In Colab" don't render correctly

[tvalentyn]

What happened?

Some images for Run In Colab buttons on
https://beam.apache.org/get-started/an-interactive-overview-of-beam/ and possibly other places don't render correctly.

Issue Priority

Priority: 2 (default / most bugs should be filed as P2)

Issue Components

• Component: Python SDK
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[tvalentyn]

cc: @aIbrahiim perhaps you could TAL. thanks.