Fix HistoryExport retry_policy assertion for JSON key-order variance

MySQL 8's JSON type normalizes object keys by length ascending, so a
retry_policy stored as [snapshot_version, max_attempts, backoff_seconds]
reads back as [max_attempts, backoff_seconds, snapshot_version]. The
in-memory Eloquent cast keeps the original insertion order, so the
bundle's policy (reloaded from the DB) and the model's in-memory policy
disagree on key order but not on values. `assertSame` is key-order
sensitive and failed on every v2 run.

Switch the single offending assertion to `assertEquals`, which compares
values the way JSON semantics actually are. All 18 HistoryExportTest
tests now pass against MySQL 8.

Author: durable-workflow-ops

tests/Unit/V2/HistoryExportTest.php

@@ -429,7 +429,10 @@ public function testItBuildsVersionedReplayBundleFromTypedHistoryAndProjections(
         $this->assertSame($activity->id, $bundle['activities'][0]['id']);
         $this->assertSame($activity->id, $bundle['activities'][0]['idempotency_key']);
         $this->assertTrue($bundle['activities'][0]['diagnostic_only']);
-        $this->assertSame($activity->retry_policy, $bundle['activities'][0]['retry_policy']);
+        // retry_policy is JSON-cast and key order is not preserved across
+        // DB engines (MySQL 8 sorts JSON object keys by length). The contract
+        // is value equality, not insertion order.
+        $this->assertEquals($activity->retry_policy, $bundle['activities'][0]['retry_policy']);
         $this->assertSame($attempt->id, $bundle['activities'][0]['attempts'][0]['id']);
         $this->assertSame($childCallId, $bundle['links']['children'][0]['child_call_id']);