build: Pin setuptools and setuptools-scm versions during tox build.

Author: seifertm

dependencies/default/constraints.txt

@@ -20,6 +20,8 @@ pluggy==1.6.0
 Pygments==2.19.2
 pytest==8.4.1
 requests==2.32.4
+setuptools==80.9.0
+setuptools-scm==8.3.0
 snowballstemmer==3.0.1
 sortedcontainers==2.4.0
 Sphinx==8.0.2

tox.ini

@@ -5,6 +5,9 @@ isolated_build = true
 passenv =
     CI
 
+[pkgenv]
+constraints = dependencies/default/constraints.txt
+
 [testenv]
 package = wheel
 wheel_build_env = .pkg