The "other" robot framework SerialLibrary: https://github.com/whosaysni/robotframework-seriallibrary installs as "SerialLibrary" (with inner init.py files) where as this one installs as "SerialLibrary.py"
This means they can both technically be installed at the same time, but there's no way to include this one anymore. Attempting a direct "Library SerialLibrary.py" looks for a "py" class inside the SerialLibary module.
Please consider using a non-conflicting name for this package, so that both can be used side by side, or at least without confusing conflicts