Project keys can not contain slashes (“/”) as suggested by the error message
Allowed characters are alphanumeric, ‘-’, ‘_’, ‘.’ and ‘:’, with at least one non-digit
The new key must contain at least one non-digit character. Allowed characters are: ‘a’ through ‘z’, ‘A’ through ‘Z’, ‘-’ (dash), ‘_’ (underscore), ‘.’ (dot), ‘:’ (colon) and digits ‘0’ to ‘9’.
One possible workaround would be to have a preliminary step before your curl command such that you replace the slashes with one of the accepted character (eg underscore “_”)