Fix the speculos version

Since speculos.0.3.0 makes the ragger navigator act abnormally on
new-tezos-app tests with the nanox device.

The empty values, resulting from the call to
`/events?currentscreenonly=true` when signing the operation, prevent
the ragger navigator from detecting the "Accept" page.

test/python/requirements.txt

@@ -1,4 +1,5 @@
 ledger-bitcoin>=0.0.3
+speculos < 0.3.0
 ragger[tests,speculos] >= 1.9.2
 protobuf==3.20.0
 stellar_sdk