Improvement: Refactor code to use dict.get() method

## Description
As a developer,
I need code to be consistent and error-free.

## Mocks
https://github.com/anitab-org/bridge-in-tech-backend/blob/68d8ff9a8640cef1d3e53b2b0dd9b80e3d750fd7/app/api/validations/organization.py#L32-L34
For example this can be replaced by the get method i.e. data.get("KEY", "DEFAULT_VALUE") to avoid KeyError

## Acceptance Criteria
### Update [Required]
- [ ] Use get method in all code to avoid the raise of KeyError.
- [ ] Handle exceptions for default value.

## Definition of Done
- [ ] All of the required items are completed.
- [ ] Approval by 1 mentor.

## Estimation
2 hours