fix: update ec2 instance type

[infracost-autofix]

💰 Infracost opened this pull request as part of the following campaign:

Policy: AWS EC2 - consider using Graviton instances Graviton instances are around 20% cheaper than equivalent x86 instances.	Potential savings: $981/yr
Risk: Medium Migrating to ARM64 requires application and OS compatibility validation.
Deployment details: requires downtime, see AWS docs for details Replacement of the existing instance with a new Graviton‑based instance causes a new instance to be launched and the old instance to be deployed. You may wish to deploy the new instance first before terminating the old instance. If required you will need to manually migrate any on‑instance data after the new instance is deployed.

Next steps:
✅ Deploy this change before the campaign deadline: June 31
💬 Doesn't apply? Close the PR with a comment
🛠️ Needs changes? Check out the branch to rebase or adjust

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