fix(deps): restore php81 signer repository

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

Author: vitormattos

composer.json

@@ -58,6 +58,12 @@
 			"OCA\\Libresign\\Tests\\Fixtures\\": "tests/php/fixtures/"
 		}
 	},
+	"repositories": [
+		{
+			"type": "vcs",
+			"url": "https://github.com/vitormattos/pdf-signer-php"
+		}
+	],
 	"require": {
 		"cweagans/composer-patches": "^2.0",
 		"jeidison/signer-php": "dev-feat/visible-signature-appearance-php81",