Add release note about pyscf on Windows (#114)

* Add release note about pyscf on Windows

0b4558d drops the pyscf requirement on Windows because it fails
to install there.  I pushed that to main hastily and accidentally,
when I intended to make a pull request.  This follows that up with
a release note, which we should also backport to the stable/0.8
branch.

* Update release note with reminder that win32 remains unsupported

releasenotes/notes/pyscf-win32-6e4a47d11576aa47.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    pyscf is no longer considered a dependency on Windows, where it fails to
+    install.  However, Windows remains an unsupported platform.