chore(deps): bump symfony/polyfill-php81 from 1.30.0 to 1.31.0

Bumps [symfony/polyfill-php81](https://github.com/symfony/polyfill-php81) from 1.30.0 to 1.31.0.
- [Commits](symfony/polyfill-php81@v1.30.0...v1.31.0)

---
updated-dependencies:
- dependency-name: symfony/polyfill-php81
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

UPGRADE-5.7.md

@@ -35,7 +35,7 @@ This changelog references changes done in Shopware 5.7 patch versions.
 * Updated `setasign/fpdf` to version 1.8.6
 * Updated `setasign/fpdi` to version 2.6.0
 * Updated `symfony/polyfill-php80` to version 1.30.0
-* Updated `symfony/polyfill-php81` to version 1.30.0
+* Updated `symfony/polyfill-php81` to version 1.31.0
 * Updated `symfony/polyfill-php82` to version 1.30.0
 * Updated `symfony/polyfill-php83` to version 1.30.0
 * Updated `symfony/http-kernel` to version 4.4.51