fix: resend host domain key

[danilowoz]

Description

Fix an issue where the domain key was using the wrong host value.

Type of change

Please mark options that are relevant.

• New template
• Bug fix (non-breaking change which fixes an issue in the template)
• New feature (non-breaking change which adds functionality to the template)
• Breaking change (fix or feature that would cause existing template behavior to be not backward compatible)

How Has This Been Tested?

Please mark the following checks done

• Schema validated using JSON Schema template.schema
• Template functionality checked using Online Editor
• Template is checked using template linter
• Template file name follows the pattern <providerId>.<serviceId>.json

Example variable values

region: us-east-1
publicKey: RANDOM-VALUE

[github-actions]

Linter OK:

Linter result for resend.com.mail.json

[pawel-kow]

LGTM!