tox: workaround test failures for schemacheck

Python packaging is being annoying today.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

tox.ini

@@ -57,10 +57,18 @@ commands =
 
 [testenv:schemacheck]
 deps =
-    black
+    black>=21.8b0, <23.11
     PyYAML
 commands =
     python -m sambacc.schema.tool
+# The following env var is a workaround for running this testenv on fedora 39
+# with python 3.12.1. As of approx. 2023-12-11 the ci started # to fail because
+# of the multidict library (not even one of our direct dependencies) failing
+# to install from source because we (intentionally) have no C compiler in the
+# image. Try to remove this in a few weeks to see if wheel availability or
+# whatever has been resolved.
+setenv =
+    MULTIDICT_NO_EXTENSIONS=1
 
 # this gitlint rule is not run by default.
 # Run it manually with: tox -e gitlint