[sitecore-jss-nextjs] Ensure locales are compared case-insensitively in redirects middleware

[art-alexeyenko]

• This PR follows the Contribution Guide
• Changelog updated
• Upgrade guide entry added

Description / Motivation

We must ensure redirect rules specified like 'pl-pl/mypath' would still activate if matching 'pl-PL' locale, despite difference in case.

Testing Details

• Unit Test Adjusted
• Manual Test/Other (Please elaborate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[yavorsk]

Looks good. However I am thinking, does it make sense to add a test for case sensitive path redirect with and without locale?

[art-alexeyenko]

@yavorsk

However I am thinking, does it make sense to add a test for case sensitive path redirect with and without locale?

The existing unit test already tests for lowercase locale in redirect pattern, I think we're covered here.