Modified logo_link to work with latest theme version (#6209)

* modified logo_link to work with new sphinx schema

* Make black happy

Co-authored-by: Michael Osthege <michael.osthege@outlook.com>

docs/source/conf.py

@@ -252,7 +252,9 @@ def setup(app):
             "icon": "fab fa-discourse",
         },
     ],
-    "logo_link": "https://www.pymc.io",
+    "logo": {
+        "link": "https://www.pymc.io",
+    },
     "show_prev_next": False,
     "navbar_start": ["navbar-logo", "navbar-version"],
     "navbar_end": ["navbar-icon-links.html"],