Update jangregor/phpstan-prophecy requirement from ^0.6.2 to ^0.7.0

Updates the requirements on [jangregor/phpstan-prophecy](https://github.com/Jan0707/phpstan-prophecy) to permit the latest version.
- [Release notes](https://github.com/Jan0707/phpstan-prophecy/releases)
- [Changelog](https://github.com/Jan0707/phpstan-prophecy/blob/master/CHANGELOG.md)
- [Commits](Jan0707/phpstan-prophecy@0.6.2...0.7.0)

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

composer.json

@@ -30,7 +30,7 @@
         "slim/slim": "^4.5"
     },
     "require-dev": {
-        "jangregor/phpstan-prophecy": "^0.6.2",
+        "jangregor/phpstan-prophecy": "^0.7.0",
         "phpstan/phpstan": "^0.12.25",
         "phpunit/phpunit": "^8.5"
     },