fix: switch instance to graviton

[infracost-fixer]

Infracost created this pull request, see issue details here

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[github-actions]

💰 Infracost report

Monthly estimate decreased by $111 📉

Changed project	Module path	Baseline cost	Usage cost*	Total change	New monthly cost
infra_aws		-$111	+$0	-$111 (-10%)	$1,006

*Usage costs were estimated using infracost-usage.yml, see docs for other options.

Estimate details

Key: * usage cost, ~ changed, + added, - removed

──────────────────────────────────
Project: infra_aws

~ aws_instance.web_app
  -$111 ($680 → $569)

    ~ Instance usage (Linux/UNIX, on-demand, m5.4xlarge → m6g.4xlarge)
      -$111 ($561 → $450)

Monthly cost change for infra_aws
Amount:  -$111 ($1,117 → $1,006)
Percent: -10%

──────────────────────────────────
Key: * usage cost, ~ changed, + added, - removed
4 projects have no cost estimate changes.
Run the following command to see their breakdown: infracost breakdown --path=/path/to/code

──────────────────────────────────
*Usage costs were estimated using infracost-usage.yml, see docs for other options.

12 cloud resources were detected:
∙ 10 were estimated
∙ 2 were free

Infracost estimate: Monthly estimate decreased by $111 ↓
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┓
┃ Changed project                                    ┃ Baseline cost ┃ Usage cost* ┃ Total change ┃
┣━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━╋━━━━━━━━━━━━━━┫
┃ infra_aws                                          ┃         -$111 ┃         +$0 ┃ -$111 (-10%) ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━┻━━━━━━━━━━━━━━┛

_{This comment will be updated when code changes.}