[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).

removing the python-zmq from bindep as that is py2 things and not
available/needed for Focal/Victoria testing.

Fixing:
- bug#1886298
Bump the lower constraints for required deps which added python3.8
support in their later version.
Story: #2007865
Task: #40216

Closes-Bug: #1886298

[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-focal

Change-Id: If68e8dcb2295267195acc4918abe5167e863a7f2

bindep.txt

@@ -24,7 +24,6 @@ pkgconfig [platform:rpm]
 python-dev [platform:dpkg]
 python-devel [platform:rpm]
 python-lxml
-python-zmq
 python3-all-dev [platform:ubuntu !platform:ubuntu-precise]
 python3-dev [platform:dpkg]
 python3-devel [platform:fedora]

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
 ddt==1.0.1
 debtcollector==1.2.0
 decorator==3.4.0
@@ -70,7 +70,7 @@ prettytable==0.7.2
 pycparser==2.18
 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