upgrade flask packages to satisfy safety check (#1313)

### Feature or Bugfix
- Bugfix

### Detail
[70813](https://data.safetycli.com/v/70813/97c/)


### Security
Please answer the questions below briefly where applicable, or write
`N/A`. Based on
[OWASP 10](https://owasp.org/Top10/en/).

- Does this PR introduce or modify any input fields or queries - this
includes
fetching data from storage outside the application (e.g. a database, an
S3 bucket)?
  - Is the input sanitized?
- What precautions are you taking before deserializing the data you
consume?
  - Is injection prevented by parametrizing queries?
  - Have you ensured no `eval` or similar functions are used?
- Does this PR introduce any functionality or component that requires
authorization?
- How have you ensured it respects the existing AuthN/AuthZ mechanisms?
  - Are you logging failed auth attempts?
- Are you using or adding any cryptographic features?
  - Do you use a standard proven implementations?
  - Are the used keys controlled by the customer? Where are they stored?
- Are you introducing any new policies/roles/users?
  - Have you used the least-privilege principle? How?


By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

backend/requirements.txt

@@ -3,8 +3,8 @@ aws-xray-sdk==2.4.3
 boto3==1.26.95
 botocore==1.29.95
 fastapi == 0.109.2
-Flask==2.3.2
-flask-cors==3.0.10
+Flask==3.0.3
+flask-cors==4.0.1
 nanoid==2.0.0
 opensearch-py==1.0.0
 PyAthena==2.3.0