Fix: Prevent duplicated column error in Event Tickets migration

[pauloiankoski]

Description

When running automated tests, database tables are truncated while preserving the effects of migrations. Recently, we introduced a migration that modifies the give_event_tickets table by adding a new amount column. However, since migrations are executed repeatedly after each database refresh (before most tests run), this led to an error when attempting to add the amount column multiple times.

To address this issue, this PR replaces the existing query execution method with a conditional check using maybe_add_column. This ensures the ALTER TABLE query is only executed if the column does not already exist, preventing redundant operations and errors.

Note: since a reformat operation has been performed in the file, note that the main change is located at the line 71.

Affects

Event Tickets migrations

Testing Instructions

1. Run unit tests then ensure no DB errors are returned.
2. Ensure the give_event_tickets is still being modified to have the new amount column.

Pre-review Checklist

• Acceptance criteria satisfied and marked in related issue
• Relevant @unreleased tags included in DocBlocks
• Includes unit tests
• Reviewed by the designer (if follows a design)
• Self Review of code and UX completed

[jonwaldstein]

👍