test: add case insensitivity test for mainnet address

[GeinerGV]

No description provided.

[Copilot]

Pull Request Overview

This PR adds a test case to verify case insensitivity for mainnet addresses in the DID Ethereum library and performs minor maintenance updates.

• Adds a test to verify that mainnet addresses are handled correctly regardless of case
• Updates package version from 0.1.5 to 0.1.6
• Moves dotenv from dependencies to devDependencies

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
package.json	Version bump and dependency reorganization
tests/create.test.ts	Added case insensitivity test for mainnet addresses

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