Bump stripe/stripe-php from 19.4.0 to 20.0.0 in /frontend (#1615)

Bumps [stripe/stripe-php](https://github.com/stripe/stripe-php) from 19.4.0 to 20.0.0.
- [Release notes](https://github.com/stripe/stripe-php/releases)
- [Changelog](https://github.com/stripe/stripe-php/blob/master/CHANGELOG.md)
- [Commits](stripe/stripe-php@v19.4.0...v20.0.0)

---
updated-dependencies:
- dependency-name: stripe/stripe-php
  dependency-version: 20.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

frontend/composer.json

@@ -16,7 +16,7 @@
         "yiisoft/yii2-bootstrap": "~2.0.11",
         "yiisoft/yii2-bootstrap4": "^2.0.11",
         "overals/yii2-whois": "~1.0.2",
-        "stripe/stripe-php": "^19.1",
+        "stripe/stripe-php": "^20.0",
         "yiisoft/yii2-symfonymailer": "^4.0.0",
         "echoctf/identicon": "^2.0",
         "cebe/markdown": "^1.2",