fix #79 - Githubissues

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What is the motivation?

The current HTTP client has no method merge to partially update record(s) by performing a query like

UPDATE person:tobbie MERGE {
    settings: {
        active: true
    }
};

So I solved it according to the official documentation from https://surrealdb.com/docs/integration/http#modify-one.

[ ] 📚 Examples / docs / tutorials / dependencies update
[x] 🔧 Bug fix (non-breaking change which fixes an issue)
[ ] 🥂 Improvement (non-breaking change which improves an existing feature)
[x] 🚀 New feature (non-breaking change which adds functionality)
[ ] 💥 Breaking change (fix or feature that would cause existing functionality to change)
[ ] 🔐 Security fix

Adding the merge method to class SurrealHTTP.

db = SurrealHTTP(...)
await db.merge('person:tobbie', {
    'settings': {
        'active': True
    }
})

which should and did output the modified record.