Bump phpstan/phpstan from 0.11.12 to 0.11.15
Bump phpstan/phpstan from 0.11.12 to 0.11.15

Bumps [phpstan/phpstan](https://github.com/phpstan/phpstan) from 0.11.12 to 0.11.15.
- [Release notes](https://github.com/phpstan/phpstan/releases)
- [Commits](https://github.com/phpstan/phpstan/compare/0.11.12...0.11.15)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
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