[Composer] Bump guzzlehttp/guzzle to version 7 to suppress deprecation notices

- Bump divineomega/password_exposed to version 3 to remove dependency on Guzzle version 6
- Add new ICanHandleHttpResponses->getBodyString method to solve inheritance mismatch with GuzzleHttp\Psr7\ResponseInterface->getBody return type

src/Security/ExAuth.php

@@ -250,7 +250,7 @@ class ExAuth
 			return false;
 		}
 
-		$json = @json_decode($curlResult->getBody());
+		$json = @json_decode($curlResult->getBodyString());
 		if (!is_object($json)) {
 			return false;
 		}