Fix error message

Author: Art4

tests/RedmineExtension/RedmineInstance.php

@@ -101,7 +101,7 @@ private function runHealthChecks(RedmineVersion $version): void
 
         if ($data === false || $statusCode !== 200) {
             throw new InvalidArgumentException(sprintf(
-                'Could not connect to Redmine server at %s, please make sure that Redmine %s has running a docker service in /docker-composer.yml and is correctly configured in /tests/Behat/behat.yml.',
+                'Could not connect to Redmine server at %s, please make sure that Redmine %s has a docker service in /docker-composer.yml and is correctly configured in /tests/Behat/behat.yml.',
                 $this->redmineUrl,
                 $version->asString(),
             ));