Drop testing on Bionic and Python36

Bionic is on its way out due to lack of support in modern Ansible
releases and thus Zuul. Drop the bionic python36 job and replace it with
a focal python38 job. Update the setup.cfg trove attributes to match.

Change-Id: I2d1a29439e1b6979ba645a34e68e2d727c2decf2

.zuul.yaml

@@ -1,7 +1,7 @@
 - job:
-    name: nox-py36-gerrit-default
-    parent: nox-py36
-    nodeset: ubuntu-bionic
+    name: nox-py38-gerrit-default
+    parent: nox-py38
+    nodeset: ubuntu-focal
 
 - job:
     name: nox-py312-gerrit-310
@@ -28,7 +28,7 @@
       jobs: &jobs
         - build-python-release
         - nox-linters
-        - nox-py36-gerrit-default
+        - nox-py38-gerrit-default
         - nox-py312-gerrit-310
         - nox-py312-gerrit-311
     gate:

bindep.txt

@@ -2,5 +2,5 @@
 # install and tests; see http://docs.opendev.org/opendev/bindep/ for additional
 # information.
 
-openjdk-11-jdk [test platform:ubuntu-bionic]
+openjdk-11-jdk [test platform:ubuntu-focal]
 openjdk-21-jdk [test platform:ubuntu-noble]

setup.cfg

@@ -23,15 +23,13 @@ classifiers =
     License :: OSI Approved :: Apache Software License
     Operating System :: OS Independent
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.6
-    Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
     Programming Language :: Python
     Topic :: Utilities
-python_requires = >= 3.6
+python_requires = >= 3.8
 
 [files]
 packages =