chore: remove PNG namespace override helper

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

composer.json

@@ -25,9 +25,6 @@
     }
   },
   "autoload-dev": {
-    "files": [
-      "tests/Support/PngNamespaceFunctionOverrides.php"
-    ],
     "psr-4": {
       "LibreSign\\XObjectTemplate\\Tests\\": "tests/"
     }