chore: use external injective-testing

[mmeloni]

this PR move outside injective-testing dep using https://github.com/InjectiveLabs/injective-testing repo. ATM it uses a local package. We will switch soon to the public crate

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch chore/simp-dep

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