You may avoid this error by adding geyser_streamlit_dashboard/__init__.py as a workaround.
Poetry tries to install the geyser_streamlit_dashboard package and emits the error because it cannot be found actually.
We can avoid this problem by adding --no-root option in your local env, but we don’t have a control on Streamlit Cloud, so all we can do is to add such a dummy file.
FYI,
I created a feature request issue about it: Streamlit Cloud should support the --no-root option for poetry install · Issue #6117 · streamlit/streamlit · GitHub