[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.

Story: #2007865
Task: #40198

Closes-Bug: #1886298

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

Change-Id: If52778edf7ab5ade5794f12d9d167d6ad562b983

lower-constraints.txt

@@ -1,11 +1,11 @@
 alabaster==0.7.10
 appdirs==1.3.0
 asn1crypto==0.23.0
-cffi==1.7.0
+cffi==1.14.0
 cliff==2.8.0
 cmd2==0.8.0
 coverage==4.0
-cryptography==2.1
+cryptography==2.7
 debtcollector==1.2.0
 decorator==3.4.0
 deprecation==1.0
@@ -26,7 +26,7 @@ jsonpointer==1.13
 jsonschema==2.6.0
 keystoneauth1==3.4.0
 linecache2==1.0.0
-MarkupSafe==1.0
+MarkupSafe==1.1.1
 monotonic==0.6
 mox3==0.20.0
 msgpack-python==0.4.0
@@ -65,7 +65,7 @@ python-keystoneclient==3.8.0
 python-mimeparse==1.6.0
 python-subunit==1.0.0
 pytz==2013.6
-PyYAML==3.12
+PyYAML==3.13
 requests==2.14.2
 requests-mock==1.1.0
 requestsexceptions==1.2.0

requirements.txt

@@ -8,7 +8,7 @@ python-keystoneclient>=3.8.0 # Apache-2.0
 iso8601>=0.1.11 # MIT
 pyOpenSSL>=17.1.0 # Apache-2.0
 requests>=2.14.2 # Apache-2.0
-PyYAML>=3.12 # MIT
+PyYAML>=3.13 # MIT
 yaql>=1.1.3 # Apache 2.0 License
 osc-lib>=1.8.0 # Apache-2.0
 murano-pkg-check>=0.3.0 # Apache-2.0