Bump minimum testbench version to fix prefer-lowest CI

Testbench v9.0.0/9.0.1 has a bug with undeclared $latestResponse
static property that causes all tests to fail.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: aarondfrancis

composer.json

@@ -19,7 +19,7 @@
         "aws/aws-sdk-php": "^3.216.1"
     },
     "require-dev": {
-        "orchestra/testbench": "^8|^9|^10",
+        "orchestra/testbench": "^8.23|^9.1|^10",
         "mockery/mockery": "^1.3.3",
         "phpunit/phpunit": "^9|^10|^11"
     },