PSM3 updates (#1086)

* psm3 updates

* updates from review

* Update pvlib/iotools/psm3.py

Co-authored-by: Will Holmgren <[email protected]>

* whatsnew

Co-authored-by: Will Holmgren <[email protected]>

Author: kandersolar

docs/sphinx/source/whatsnew/v0.8.1.rst

@@ -17,7 +17,8 @@ Enhancements
   option to :py:class:`~pvlib.modelchain.ModelChain`. (:pull:`1042`) (:issue:`1073`)
 * Added :py:func:`pvlib.temperature.ross` for cell temperature modeling using
   only NOCT. (:pull:`1045`)
-
+* Added optional ``attributes`` parameter to :py:func:`pvlib.iotools.get_psm3`
+  and added the option of fetching 5- and 15-minute PSM3 data. (:pull:`1086`)
 
 Bug fixes
 ~~~~~~~~~