Switch to pytest

nose has not seen active development for many years now. With py310, we
can no longer use it due to import errors.

Also update lower contraints

Closes-Bug: #1993531
Change-Id: I215ba0d4654c9c637c3b97953d8659ac80892db8

tools/playbooks/common/install_dependencies.yaml

@@ -35,14 +35,17 @@
     - name: install python modules with pip
       pip: name={{ item }} state=present extra_args='--upgrade'
       with_items:
+        # For some reason, pip on py2 isn't smart enough to prevent us
+        # trying to install a too-new mock or attrs??
+        - 'mock<4'
+        - 'attrs<22.1.0'
+        # Order matters; install constrained versions *first*, then unconstrained
         - crudini
         - eventlet
-        - nose
         - pyeclib
+        - pytest
+        - pytest-cov
         - python-swiftclient
-        # For some reason, pip on py2 isn't smart enough to prevent us
-        # trying to install a too-new mock??
-        - 'mock<4'
 
     - name: install PasteDeploy - CentOS 7
       pip: name={{ item }} state=present extra_args='--upgrade'

tools/playbooks/probetests/run.yaml

@@ -21,6 +21,6 @@
       shell:
         cmd: |
           source ~/.bashrc
-          nosetests test/probe/ --with-id || nosetests --failed
+          pytest test/probe/ || pytest --last-failed test/probe/
         executable: /bin/bash
         chdir: '{{ zuul.project.src_dir }}'