[DerManoMann]

Third part of the new shape for 3.0, and the last change to the adapters' API. Both middleware used to fetch the test case back out of the container under OPENAPI_VERFIER_CONTAINER_KEY, just to call its trait methods. They get an OpenApiVerifier now, and the key is gone.

• PSR-15: Adapters\Psr15\OpenApiVerifierMiddleware is new, and works with any PSR-15 stack. A mismatch throws OpenApiSchemaMismatchException, and an optional callback runs first, to report it in a way of its own.
• Slim: the trait registers the PSR-15 middleware, with a callback that fails the test. Adapters\Slim\OpenApiVerifierMiddleware and the probing for a usable container are removed. Since Add OpenApiVerifier, and match paths against the specification's templates #78 matches paths against the specification, the verifier no longer has to be registered before the routing middleware. A new test registers it after routing.
• Laravel: the middleware takes the verifier and the callback in its constructor. The trait binds that instance under the middleware's class name, and the kernel resolves the same instance for handle() and terminate().

Also in here, since this is the breaking slice: $openapiSpecification gets its real type, object|string|null with a null default, and failSchemaMismatch() builds its message with implode() instead of an eight-placeholder sprintf. Adapters\PSR17Middleware goes, and psr/http-server-middleware is required, interface-only like the other PSR packages.

How a test class uses the adapters does not change: registerOpenApiVerifier() is called the same way. The phpstan baseline drops from 12 entries to 5. What went were findings from the old design, which typed the verifier it fetched as VerifiesOpenApi, a trait, so none of the calls on it could be checked. Checked locally with highest and lowest dependencies.