Fix for mindeps build (fails on latest attrs) (#475)

Author: sirosen

tox.ini

@@ -18,6 +18,9 @@ description = "run tests with pytest"
 usedevelop = true
 extras = dev
 deps =
+# attrs v23.2.0 is needed for mindeps because jsonschema==4.18.0
+# is uses `hash=True` which was deprecated after this version
+    mindeps: attrs==23.2.0
     mindeps: jsonschema==4.18.0
     mindeps: click==8.0.0
     mindeps: requests==2.0.0