[arng4108]

🗣 Description

Add models.py model for the table "whoisxml_reverse_dns_cache" that's been created in the P&E database. This model will allow for future caching solution implementations to query the cache table via the P&E API

💭 Motivation and context

We need to create a corresponding model in models.py for the whoisxml_reverse_dns_cache table in the P&E database so that the whoisxml caching solution script and ASM Sync script are able to query the cache table using the P&E API

🧪 Testing

Tested locally by adding model to models.py and running Makefile build/start/syncdb-populate and confirming that the resulting table that is set up locally matches the real table in the PE database. Also verified that table name, column names, data types, and constraints match as well.

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
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• All future TODOs are captured in issues, which are referenced in code comments.
• All relevant type-of-change labels have been added.
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✅ Pre-merge checklist

• Revert dependencies to default branches.
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✅ Post-merge checklist

• Create a release (necessary if and only if the version was bumped).