Pin pip packages to stay with python2

Change-Id: Ibd3b9883130d57afbd7f6bacaecf7fec467996e7
Related-Prod: PROD-34533
diff --git a/src/com/mirantis/mk/Python.groovy b/src/com/mirantis/mk/Python.groovy
index 496e6f5..29288f9 100644
--- a/src/com/mirantis/mk/Python.groovy
+++ b/src/com/mirantis/mk/Python.groovy
@@ -90,7 +90,7 @@
  */
 def setupDocutilsVirtualenv(path, python="python2") {
     requirements = [
-      'docutils',
+      'docutils==0.16',
     ]
     setupVirtualenv(path, python, requirements)
 }
@@ -371,8 +371,8 @@
  */
 def setupJinjaVirtualenv(path) {
     requirements = [
-      'jinja2-cli',
-      'pyyaml',
+      'jinja2-cli==0.7.0',
+      'pyyaml==5.3',
     ]
     setupVirtualenv(path, 'python2', requirements)
 }