feat(pkginfo): upgrade python-dateutil to ">=2.8.0,<2.9.0"

cubicweb_saem_ref/__pkginfo__.py

@@ -27,7 +27,7 @@ __depends__ = {
     'cubicweb-vtimeline': ">=0.6.0,<0.7.0",
     'cubicweb-signedrequest': ">=1.0.0,<1.1.0",
     'isodate': None,
-    'python-dateutil': None,
+    'python-dateutil': ">=2.8.0,<2.9.0",
     'pytz': ">=2020.5.0,<2020.6.0",
     'psycopg2': ">=2.8.0,<2.9.0",
     'rdflib': ">=5.0.0,<5.1.0",