Fix asyncpg rollback example

[dikshant]

Dikshant Adhikari (dikshant) commented:

https://github.com/cockroachdb/example-app-python-asyncpg/blob/main/example.py#L86

uses conn.rollback() which is not a thing. We are doing async with conn.transaction(): we should do async with conn.transaction() as t: and then t.rollback() instead of conn.rollback() because rollbacks are defined at the transaction level and not the connection level
https://magicstack.github.io/asyncpg/current/api/index.html#asyncpg.transaction.Transaction

time.sleep should also be updated to use await async.io sleep as a best practie
https://github.com/cockroachdb/example-app-python-asyncpg/blob/main/example.py#L90

Jira Issue: DOC-9106

[exalate-issue-sync]

Shannon Bradshaw (shannonbradshaw) commented:
Dikshant Adhikari, in what context did you come across this?

[exalate-issue-sync]

Dikshant Adhikari (dikshant) commented:
Shannon Bradshaw Someone from the community slack flagged it
https://cockroachdb.slack.com/archives/C01LKHP0KS6/p1698181388311639

[exalate-issue-sync]

Richard Loveland (rmloveland) commented:
Dikshant Adhikari I snagged this and added a prio, plz feel free to change it if you disagree