fix(chain): updated nativeCurrency decimal for defichainEvmTestnet and defichainEvm

[fullstackninja864]

This PR update nativeCurrency decimal for defichainEvm (mainnet) and defichainEvmTestnet (testnet) chain definition.

Detailed summary
We are getting this error while connecting to defichainEvm/defichainEvmTestnet network (as below)
This issue is related to miss match with decimal place.

MetaMask - RPC Error: Expected the number 18 for 'nativeCurrency.decimals' when 'nativeCurrency' is provided. Received: 8 {code: -32602, message: "Expected the number 18 for 'nativeCurrency.decimals' when 'nativeCurrency' is provided. Received: 8", stack: '{\n  "code": -32602,\n  "message": "Expected the num…ogaeaoehlefnkodbefgpgknn/background-4.js:3:56371)'}

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PR-Codex overview

This PR updates the decimals for DeFiChain from 8 to 18 in defichainEvm.ts and defichainEvmTestnet.ts, and also adjusts the nativeCurrency for these chains.

Detailed summary

• Updated decimals for DeFiChain from 8 to 18 in defichainEvm.ts and defichainEvmTestnet.ts
• Adjusted nativeCurrency for defichainEvmTestnet and defichainEvm

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🦋 Changeset detected

Latest commit: e22c41b

The changes in this PR will be included in the next version bump.

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viem	Patch

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