Fix reset-postgres task volume name

[PrateekKumar1709]

Problem Statement
Fix volume name in reset-postgres task

Related Issue
Fixes #17

Proposed Changes

• Added vars section at the top of the taskfile to define COMPOSE_FILE and POSTGRES_VOLUME_NAME variables.
• Updated all docker compose commands to use {{.COMPOSE_FILE}} instead of hardcoding the path.
• In the reset-postgres task, replaced 'odr_database_postgres_data' with {{.POSTGRES_VOLUME_NAME}}.
• Used Task's variable expansion syntax ({{.VAR_NAME}}) throughout the file for consistency and to ensure proper variable expansion.

These changes ensure that the correct volume name (omi-postgres_postgres_data) is used when resetting the Postgres database, resolving the "no such volume" error previously encountered.

Testing:

• Verified that all postgres-related tasks work as expected, especially the reset-postgres task.
• Confirmed that the volume is correctly removed and recreated during reset.

[CheesyLaZanya]

Volume name looks to be updated correctly and additional enhancements seem reasonable so looks good to me.