Exclude from composer vendor bundle /tests and /phpunit.xml.dist

They are not .gitattributes removed because the files are needed at Debian.
But people using the files with composer do not need them.

Closes: #379

Signed-off-by: William Desportes <williamdes@wdes.fr>

composer.json

@@ -61,5 +61,11 @@
             "dealerdirect/phpcodesniffer-composer-installer": true,
             "phpstan/extension-installer": true
         }
+    },
+    "archive": {
+        "exclude": [
+            "/tests",
+            "/phpunit.xml.dist"
+        ]
     }
 }