package/python-ecdsa: add PYTHON_ECDSA_CPE_ID_VENDOR

cpe:2.3:a:python-ecdsa_project:python-ecdsa is a valid CPE identifier
for this package:

  https://nvd.nist.gov/products/cpe/search/results?namingFormat=2.3&keyword=cpe%3A2.3%3Aa%3Apython-ecdsa_project%3Apython-ecdsa



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>