refactor(v4-sdk): simplify midPrice in Route entity

[shuhuiluo]

PR Scope

Please title your PR according to the following types and scopes following conventional commits:

• fix(SDK name): will trigger a patch version
• chore(<type>): will not trigger any release and should be used for internal repo changes
• <type>(public): will trigger a patch version for non-code changes (e.g. README changes)
• feat(SDK name): will trigger a minor version
• feat(breaking): will trigger a major version for a breaking change

Description

Simplify the midPrice calculation by removing complex logic and utilizing priceOf method directly. This change improves code readability and maintainability, reducing potential points of failure.

How Has This Been Tested?

Unit tests.

Are there any breaking changes?

No.

If there are breaking changes, please ensure you bump the major version Bump the major version (by using the title feat(breaking): ...), post a notice in #eng-sdks, and explicitly notify all Uniswap Labs consumers of the SDK.

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(Optional) Follow Ups

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[ewilz]

Thanks, great usage of the pool interface.

[hensha256]

I think its erroring in CI because this is a fork PR so doesnt have access to the action env variables. We should merge into a local branch to run CI before merging :)