95-test_external_pyca_data/cryptography.py: only install for testing

Also, be less silent when installing, so possible errors are shown.

[extended tests]

Fixes #3005

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3007)

test/recipes/95-test_external_pyca_data/cryptography.sh

@@ -44,7 +44,7 @@ virtualenv venv-pycrypto
 
 cd pyca-cryptography
 
-pip install -q --requirement dev-requirements.txt
+pip install .[test]
 
 echo "------------------------------------------------------------------"
 echo "Building cryptography"