Pin urllib3 to 1.23

Due requests lib use OrderecDict from urllib3 we have to pin urllib3 to
    1.23 because OrderecDict implementation removed in 1.24

Change-Id: I1e9f21f8242f872042129ee52c026488c521cbff
diff --git a/tcp_tests/requirements.txt b/tcp_tests/requirements.txt
index f7f9c9f..54c2cdd 100644
--- a/tcp_tests/requirements.txt
+++ b/tcp_tests/requirements.txt
@@ -9,7 +9,7 @@
 pytest>=2.9,<=3.2.5
 docker-py
 docker-compose==1.7.1
-urllib3
+urllib3==1.23
 junit-xml
 jinja2>=2.9
 jira