Make SQLAlchemy optional for Postgres provider

[mohit7705]

This PR makes SQLAlchemy an optional dependency for the Postgres provider, following the same pattern already applied to other providers (for example Presto and Exasol).

Summary of changes

• Removed hard SQLAlchemy imports from module level
• Imported SQLAlchemy lazily inside methods that require it
• Raised AirflowOptionalProviderFeatureException when SQLAlchemy-dependent functionality is used without SQLAlchemy installed
• Kept SQLAlchemy as an optional extra dependency

This aligns the Postgres provider with the guidance described in the parent issue.

Note

Apologies for any confusion earlier — I had to delete the previous PR due to some local issues and have opened this new PR with the corrected and final changes.

References

• Related to: Add proper dependencies for sqlalchemy - postgres #59905
• Parent issue: Add proper dependencies for sqlalchemy - dependent providers #59895

[mohit7705]

hi @potiuk
can you pls review this ,
tell me if any correction needed .

[mohit7705]

Hi @justinpazkad @potiuk , I’m currently seeing a CI failure from a pre-commit hook related to imports in postgres.py.
I’m not fully sure whether the preferred approach here is to remove one of the imports, adjust the TYPE_CHECKING usage, or use an alternative pattern.
Could you please suggest the recommended way to handle this? Thanks!

[Prab-27]

You need to install prek hook and run prek run --all-files .this will automatically fix the static checks

[Prab-27]

We need to add dependency here : related discussion : here

[Prab-27]

@potiuk do we need to add just dependency without min version constraint ? (since min version already defined in optional dependency)
like : here