Fix copybutton for multi line examples in double digit ipython cells (#9264)

* Update conf.py

* Update whats-new.rst

Author: mosc9575

doc/conf.py

@@ -97,7 +97,7 @@
 }
 
 # sphinx-copybutton configurations
-copybutton_prompt_text = r">>> |\.\.\. |\$ |In \[\d*\]: | {2,5}\.\.\.: | {5,8}: "
+copybutton_prompt_text = r">>> |\.\.\. |\$ |In \[\d*\]: | {2,5}\.{3,}: | {5,8}: "
 copybutton_prompt_is_regexp = True
 
 # nbsphinx configurations

doc/whats-new.rst

@@ -88,7 +88,8 @@ Documentation
   By `Jessica Scheick <https://github.com/jessicas11>`_.
 - Improvements to Zarr & chunking docs (:pull:`9139`, :pull:`9140`, :pull:`9132`)
   By `Maximilian Roos <https://github.com/max-sixty>`_.
-
+- Fix copybutton for multi line examples and double digit ipython cell numbers (:pull:`9264`).
+  By `Moritz Schreiber <https://github.com/mosc9575>`_.
 
 Internal Changes
 ~~~~~~~~~~~~~~~~