Fix broken link in GitHub Contributing tab (pvlib#2806)

* fix broken contributing link

* add tzdata to fix readthedocs build

* Revert "add tzdata to fix readthedocs build"

This reverts commit 9d7b89e.

Author: yonryzhu

.github/CONTRIBUTING.md

@@ -1,4 +1,4 @@
 Contributing
 ============
 
-We welcome your contributions! Please see the [contributing](http://pvlib-python.readthedocs.io/en/latest/contributing.html) page for information about how to contribute.
+We welcome your contributions! Please see the [contributing](https://pvlib-python.readthedocs.io/en/stable/contributing/index.html) page for information about how to contribute.

docs/sphinx/source/whatsnew/v0.15.3.rst

@@ -22,6 +22,7 @@ Enhancements
 
 Documentation
 ~~~~~~~~~~~~~
+* Fix broken link in GitHub Contributing tab. (:issue:`2628`, :pull:`2806`)
 
 
 Testing
@@ -42,4 +43,4 @@ Maintenance
 
 Contributors
 ~~~~~~~~~~~~
-
+* Yonry Zhu (:ghuser:`yonryzhu`)