Disable mkdocs cross-ref strict mode

This is because of the latest marshmallow release missing symbols
causing mkdoc builds to fail.  This needs to be reverted once this is
resolved: marshmallow-code/marshmallow#2739.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

mkdocs.yml

@@ -9,7 +9,7 @@ copyright: "Copyright © 2022 Frequenz Energy-as-a-Service GmbH"
 repo_name: "frequenz-sdk-python"
 repo_url: "https://github.com/frequenz-floss/frequenz-sdk-python"
 edit_uri: "edit/v1.x.x/docs/"
-strict: true  # Treat warnings as errors
+# strict: true  # Treat warnings as errors
 
 # Build directories
 theme: