Update symfony/polyfill-php81 requirement from ^1.30 to ^1.31

Updates the requirements on [symfony/polyfill-php81](https://github.com/symfony/polyfill-php81) to permit the latest version.
- [Commits](symfony/polyfill-php81@v1.30.0...v1.31.0)

---
updated-dependencies:
- dependency-name: symfony/polyfill-php81
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

composer.json

@@ -18,7 +18,7 @@
         "php": ">=7.4",
         "seld/jsonlint": "^1.11",
         "swaggest/json-schema": "^0.12.42",
-        "symfony/polyfill-php81": "^1.30",
+        "symfony/polyfill-php81": "^1.31",
         "ext-json": "*",
         "ext-libxml": "*",
         "ext-simplexml": "*",