Added OpenAPI license SPDX id

Author: epou

tigaserver_project/settings.py

@@ -262,6 +262,8 @@
     },
     'LICENSE': {
         'name': 'GPL-3',
+        # NOTE: identifier is necessary for the openapi-generator python SDK to work.
+        'identifier': 'GPL-3.0-only',  # IMPORTANT: must be a valid SPDX identifier. See: https://spdx.org/licenses/
         'url': 'https://github.com/Mosquito-Alert/mosquito_alert/blob/master/LICENSE.md'
     },
     'SERVERS': [