[3.10] gh-145455: Constrain setuptools to a version with pkg_resources

Sphinx 3.4.3 needs this.

Author: encukou

Doc/constraints.txt

@@ -19,6 +19,7 @@ sphinxcontrib-htmlhelp<2.0.5
 sphinxcontrib-jsmath<1.1
 sphinxcontrib-qthelp<1.0.7
 sphinxcontrib-serializinghtml<1.1.10
+setuptools<82  # Setuptools with pkg_resources
 
 # Direct dependencies of Jinja2 (Jinja is a dependency of Sphinx, see above)
 MarkupSafe<2.2