Bump WooCommerce "tested up to" 8.4

[ankitguptaindia]

All Submissions:

• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?
• Will this change require new documentation or changes to existing documentation?

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Changes proposed in this Pull Request:

• Bump WooCommerce "tested up to" version 8.4.
• Bump WooCommerce minimum supported version to 8.2.
• Bump PHP minimum supported version to 7.4.

Closes #181

Steps to test the changes in this Pull Request:

1. Run the e2e test using GitHub action to test this PR with WC 8.4
2. All tests should be passed.
3. Manual Test - Plugin should give Notice when using an unsupported version of WooCommerce.

Changelog entry

Dev - Bump WooCommerce "tested up to" version 8.4.
Dev - Bump WooCommerce minimum supported version to 8.2.
Dev - Bump PHP minimum supported version to 7.4.