docs-check workflow: added missing pickleshare dependency

.github/workflows/docs-check.yml

@@ -38,6 +38,7 @@ jobs:
                   pip install EMD-signal
                   pip install cvxopt
                   pip install ts2vg
+                  pip install pickleshare
                   pip install https://github.com/neuropsychology/neurokit/zipball/dev
 
             - name: Build documentation 📜