pin sphinx-copybutton and change config

sphinx-copybutton introduced a new feature
in 0.5.1 which includes a default configuration
that breaks the regexp prompt matching scheme.

set copybutton_exclude to not include ".gp" as that's the class
where we exactly look for the prompts we are matching.

pin sphinx-copybutton at 0.5.1 to avoid future problems.

Change-Id: Ie03bc27a9190e71b63fc68b484f23e53b8cb72dc
References: executablebooks/sphinx-copybutton#185

docs/build/conf.py

@@ -45,6 +45,10 @@
     r">>> |\.\.\. |\$ |In \[\d*\]: | {2,5}\.\.\.: | {5,8}: "
 )
 copybutton_prompt_is_regexp = True
+# workaround
+# https://sphinx-copybutton-exclude-issue.readthedocs.io/en/v0.5.1-go/
+# https://github.com/executablebooks/sphinx-copybutton/issues/185
+copybutton_exclude = ".linenos"
 
 
 # tags to sort on inside of sections

docs/build/requirements.txt

@@ -6,4 +6,4 @@ python-dateutil
 Mako
 importlib-metadata;python_version<"3.8"
 importlib-resources;python_version<"3.9"
-sphinx_copybutton
+sphinx_copybutton==0.5.1