Specify XDG_RUNTIME_DIR to avoid warnings showing up in the docs (#249)

Author: hmaarrfk

.github/workflows/deploy_docs.yml

@@ -43,6 +43,7 @@ jobs:
         run: jupyter-book build docs
         env:
           DISPLAY: ":99.0"
+          XDG_RUNTIME_DIR: "/tmp/runtime-runner"
 
       # Deploy the book's HTML to gh-pages branch
       - name: GitHub Pages action