Unit testing: randomize test execution order

A recent commit 5b3f385 fixed an issue that was found in existing tests
as a result of adding a new test. This issue could have been caught
earlier by randomizing the execution order of the unit tests.

This commit adds pytest-randomly to the test requirements so that test
execution will be randomized.

continuous-integration/python-requirements/test.in

@@ -1,4 +1,5 @@
 pytest
 pytest-helpers-namespace
+pytest-randomly==3.12  # TODO: unfreeze when Python 3.7 support is dropped.
 pytest-timeout
 requests

continuous-integration/python-requirements/test.txt

@@ -1,14 +1,14 @@
 #
-# This file is autogenerated by pip-compile with python 3.10
-# To update, run:
+# This file is autogenerated by pip-compile with Python 3.11
+# by the following command:
 #
-#    pip-compile continuous-integration/python-requirements/test.in
+#    pip-compile --config=pyproject.toml continuous-integration/python-requirements/test.in
 #
 certifi==2023.5.7
     # via requests
 charset-normalizer==3.1.0
     # via requests
-exceptiongroup==1.1.1
+colorama==0.4.6
     # via pytest
 idna==3.4
     # via requests
@@ -22,14 +22,15 @@ pytest==7.3.1
     # via
     #   -r continuous-integration/python-requirements/test.in
     #   pytest-helpers-namespace
+    #   pytest-randomly
     #   pytest-timeout
 pytest-helpers-namespace==2021.12.29
     # via -r continuous-integration/python-requirements/test.in
+pytest-randomly==3.12.0
+    # via -r continuous-integration/python-requirements/test.in
 pytest-timeout==2.1.0
     # via -r continuous-integration/python-requirements/test.in
 requests==2.30.0
     # via -r continuous-integration/python-requirements/test.in
-tomli==2.0.1
-    # via pytest
 urllib3==2.0.2
     # via requests