Add PostalCodes.info resource

[PabloCirre]

Adds PostalCodes.info as a developer-facing postal-code API and dataset resource.

• My changes were made in the resources folder, not in the auto-generated README.md file or db folder
• The resource is highly or exclusively related to programming and development
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[github-actions]

New resource link: https://postalcodes.info/api

[github-actions]

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Resource Validation Errors

🔤 Alphabetical Order

• n.ts:75: Resource "NexTool" should come before "Nextradar"
• o.ts:29: Resource "Octotree" should come before "OrcaSheets"

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