Update phpspec/prophecy requirement from ^1.11 to ^1.12

Updates the requirements on [phpspec/prophecy](https://github.com/phpspec/prophecy) to permit the latest version.
- [Release notes](https://github.com/phpspec/prophecy/releases)
- [Changelog](https://github.com/phpspec/prophecy/blob/master/CHANGES.md)
- [Commits](phpspec/prophecy@1.11.0...1.12.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

composer.json

@@ -61,7 +61,7 @@
         "laminas/laminas-diactoros": "^2.3",
         "nyholm/psr7": "^1.3",
         "nyholm/psr7-server": "^1.0.0",
-        "phpspec/prophecy": "^1.11",
+        "phpspec/prophecy": "^1.12",
         "phpstan/phpstan": "^0.12.37",
         "phpunit/phpunit": "^8.5",
         "slim/http": "^1.1",