fix: aws hook should work without conn id (apache#8534)

This patch makes behavior of hook consistent with documentation.

AWS hooks should support falling back to using default credential chain
lookup behavior when connection id is not specified.
add test for conn_id equals None
more elegant way to set role session name

Pins flask-admin to 1.4.0

[hotfix] flask admin 1.4.1 break production, pinning 1.4.0

Bump version to unblock pypi release

[AIRFLOW-52] 1.7.1 version bump and changelog

Fix : Don't treat premature tasks as could_not_run tasks

Merge pull request apache#1422 from stranbird/conn-ui-revamp

Show `extra` data on the connection list view

Revert "Tasks references upstream and downstream tasks using strings …

…instead of references"

This reverts commit 6c1207b.

Revert "Tasks references upstream and downstream tasks using strings …

…instead of references"

This reverts commit 6c1207b.