[MNT] 0.21.0 release action - update sklearn bound to <1.4.0 (#4778)

Fixes #4585

Depends on #4860 for fixing
remaining issues.

pyproject.toml

@@ -49,7 +49,7 @@ dependencies = [
     "pandas>=1.1.0,<2.1.0",
     "packaging",
     "scikit-base<0.6.0",
-    "scikit-learn>=0.24.0,<1.3.0",
+    "scikit-learn>=0.24.0,<1.4.0",
     "scipy<2.0.0,>=1.2.0",
 ]