feat: update client to v25 api

[matthewmcneely]

Description

This PR updates pydgraph to Dgraph version v25

Checklist

• Code compiles correctly and linting passes locally
• For all code changes, an entry added to the CHANGELOG.md file describing and linking to
  this PR
• Tests added for new functionality, or regression tests for bug fixes added as applicable
• For public APIs, new features, etc., PR on
  docs repo staged and linked here

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✅ matthewmcneely
❌ Shiva

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[matthewmcneely]

A few more general things

• Can you add an integration test of run_dql in a namespace that's accessed by logging in with the open func using the username:password authentication in the connection string? There's new code in client.py lines 315-321 that I'm not 100% confident in
• Can you change all the copyright headers to Istari Digital ownership, should be

 # SPDX-FileCopyrightText: © 2017-2025 Istari Digital, Inc.
 # SPDX-License-Identifier: Apache-2.0

Also there are some other places where the hypermode term should be changed. Use Istari Digital, Inc. in those places. Where emails might be required, use [email protected]