There used to be a badge located here to use on GitHub for README markdown files: https://static.streamlit.io/badges/streamlit_badge_black_white.svg. It no longer appears to be there, which has broken the image link for my GitHub and others I have checked. Here is the original announcement for it, which also has a broken image link.
As this is also happening at https://github.com/streamlit/streamlit, I would guess it’s a temporary problem that hopefully will be fixed soon.
Thanks for the message, this should be resolved now!