Fixes this:
Traceback (most recent call last):
File "zuul/tools/encrypt_secret.py", line 192, in <module>
main()
File "zuul/tools/encrypt_secret.py", line 109, in main
pubkey = urlopen(req, context=ssl_ctx)
When using a file://<path> URL for the project key.
Change-Id: Ide5031eb95fda0d8932e20c178e46ba488ac1783