[goal] Migrate testing to ubuntu focal

As per victoria cycle testing runtime and community goal[1]
we need to migrate upstream CI/CD to Ubuntu Focal(20.04).

Fixing:
- bug#1886298
Bump the lower constraints for required deps which added python3.8
support in their later version.

This patch updates python version to py38 in karma.conf.js file
as py36 is not avaialbale on focal. It also adds libfontconfig1
in bindep.txt as phantomjs requires libfontconfig[2].

Story: #2007865
Task: #40201

[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-focal
[2] https://www.npmjs.com/package/phantomjs-prebuilt#linux-note

Change-Id: I4a70b7fd1ed4b94ffaed34b73779659b24e1eb65

bindep.txt

@@ -0,0 +1,4 @@
+# This is a cross-platform list tracking distribution packages needed for install and tests;
+# see https://docs.openstack.org/infra/bindep/ for additional information.
+
+libfontconfig1 [nodejs platform:dpkg]

lower-constraints.txt

@@ -3,12 +3,12 @@ appdirs==1.3.0
 asn1crypto==0.23.0
 Babel==2.3.4
 cachetools==2.0.0
-cffi==1.7.0
+cffi==1.14
 cliff==2.8.0
 cmd2==0.8.0
 contextlib2==0.4.0
 coverage==4.0
-cryptography==2.1
+cryptography==3.0
 debtcollector==1.2.0
 decorator==3.4.0
 deprecation==1.0
@@ -71,7 +71,7 @@ pycparser==2.18
 pyflakes==0.8.1
 pyinotify==0.9.6
 pymongo==3.0.2
-pyOpenSSL==17.1.0
+pyOpenSSL==19.1.0
 pyparsing==2.1.0
 pyperclip==1.5.27
 pyScss==1.3.7

octavia_dashboard/karma.conf.js

@@ -21,7 +21,7 @@ var path = require('path');
 
 module.exports = function (config) {
   // This tox venv is setup in the post-install npm step
-  var toxPath = '../.tox/karma/lib/python3.6//site-packages/';
+  var toxPath = '../.tox/karma/lib/python3.8//site-packages/';
 
   config.set({
     preprocessors: {