/usr/share/binfmts/python3.7 is in python3.7-minimal 3.7.0~b3-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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package python3.7 interpreter /usr/bin/python3.7 magic \x41\x0d\x0d\x0a