Requirements.txt: remove pyOpenSSL

It's not used anymore. Last import was removed in
Idd18ab2cdf09024f83795eaa904ec3f2815f1fc8

Change-Id: I91d6f3bed96cc71dd045aa8f8bd092caa61cc879
diff --git a/requirements.txt b/requirements.txt
index 216dd50..fdcb3d5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,7 +8,6 @@
 paramiko>=2.0 # LGPLv2.1+
 netaddr!=0.7.16,>=0.7.12 # BSD
 testrepository>=0.0.18 # Apache-2.0/BSD
-pyOpenSSL>=0.14 # Apache-2.0
 oslo.concurrency>=3.8.0 # Apache-2.0
 oslo.config>=3.12.0 # Apache-2.0
 oslo.i18n>=2.1.0 # Apache-2.0