[target-postgres] fix: Map date column to correct postgres type

[danilofuchs]

Context

Fixes #1187

Maps a JSON schema column of type string and format date to the DATE type in Postgres

We use this type extensively in our Postgres DB for data such due_date, birth_date, expiration_date, which do not contain any time/timezone info

Types of changes

What types of changes does your code introduce to PipelineWise?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)

Checklist

• I have read the CONTRIBUTING doc
• Description above provides context of the change
• I have added tests that prove my fix is effective or that my feature works
• Unit tests for changes (not needed for documentation changes)
• CI checks pass with my changes
• Branch name starts with AP-NNN (if applicable. AP-NNN = JIRA ID)
• Relevant documentation is updated including usage instructions