ECS: add declare(strict_types=1) to the dependency-analyser config

The newer ECS run on CI enforces strict_types on this root config file (the local
lock's ECS did not flag it); surfaced because this PR edits the file.

Author: loevgaard

composer-dependency-analyser.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 use ShipMonk\ComposerDependencyAnalyser\Config\Configuration;
 use ShipMonk\ComposerDependencyAnalyser\Config\ErrorType;
 
@@ -12,4 +14,4 @@
     // ignore is a no-op there, which is why unmatched-ignore reporting is disabled).
     ->ignoreUnknownClasses(['XmlWriter', 'LOCALE'])
     ->disableReportingUnmatchedIgnores()
-    ;
+;