scripts/lint-python: fix invocation in updated mypy

Mypy now is severely confused by there being a bitbox02.py inside a
bitbox02 folder, resulting in duplicate module errors. See
python/mypy#4008.

gvanrossum writes:

> This is because apparently you seem to have both a folder named gsi
and a file name gsi.py. This is a problem for Python too (IIRC the
folder/package wins) so you can't really blame mypy for complaining
about this.

I don't understand this, as Python seems to handle it fine in our
package, but mypy does not.

scripts/lint-python

@@ -23,7 +23,7 @@ ARGS=($(find py releases -name '*.py' | grep -v -e generated -e old))
 # behavior).
 # We must typecheck the whole `py` directory even if only a few files are modified so that mypy
 # sees all types
-${MYPY} --implicit-reexport --namespace-packages --ignore-missing-imports --strict py py/bitbox02 releases/describe_signed_firmware.py
+${MYPY} --implicit-reexport --namespace-packages --ignore-missing-imports --strict py/send_message.py py/bitbox02/bitbox02 releases/describe_signed_firmware.py
 
 # Must run from root directory where .pylintrc is
 # We ignore refactor and convention messages because they can differ with `black`