Bump flask from 3.1.1 to 3.1.3 in /sandbox #128

Job	Run time
Set CI/CD metadata	8s
Commit stage / Lint and validate OpenAPI	38s
Commit stage / Scan secrets	8s
Commit stage / Check file format	6s
Commit stage / Check Markdown format	5s
Commit stage / Count lines of code	11s
Commit stage / Scan dependencies	47s
Commit stage / Check English usage	10s
	2m 13s

Provide feedback