[v3-1-test] Remove duplicate cooldown-days flag in basic-tests.yml

[amoghrajesh]

https://github.com/apache/airflow/pull/59614/changes accidentally added duplicate flag leading to v3 branch being broken with:

Run prek auto-update --cooldown-days 4 --cooldown-days 4 --freeze
error: the argument '--cooldown-days <DAYS>' cannot be used multiple times

Usage: prek auto-update [OPTIONS]

For more information, try '--help'.
Error: Process completed with exit code 2.

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[amoghrajesh]

Failure is unrelated. Fixed separately

[potiuk]

🤦 ... That was a cool change :)