test: update assertion in JWTManagerTest

[kenjis]

Description
It seems the order of array items changed by the library upgrade.

1) Tests\Unit\Authentication\JWT\JWTManagerTest::testIssueAddHeader
Failed asserting that two arrays are identical.
--- Expected
+++ Actual
@@ @@
 Array &0 (
+    'typ' => 'JWT'
     'extra_key' => 'extra_value'
-    'typ' => 'JWT'
     'alg' => 'HS256'
 )

/home/runner/work/shield/shield/tests/Unit/Authentication/JWT/JWTManagerTest.php:186
phpvfscomposer:///home/runner/work/shield/shield/vendor/phpunit/phpunit/phpunit:106

https://github.com/codeigniter4/shield/actions/runs/7073301556/job/19253043215?pr=963

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide