Update symfony/yaml requirement from ^4.3 to ^5.0

Updates the requirements on [symfony/yaml](https://github.com/symfony/yaml) to permit the latest version.
- [Release notes](https://github.com/symfony/yaml/releases)
- [Changelog](https://github.com/symfony/yaml/blob/master/CHANGELOG.md)
- [Commits](symfony/yaml@v4.3.0...v5.0.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

composer.json

@@ -17,7 +17,7 @@
   "require-dev": {
     "symfony/var-dumper": "^4.0",
     "tedivm/stash": "^0.14.2",
-    "symfony/yaml": "^4.3",
+    "symfony/yaml": "^5.0",
     "bavix/tests": "^1.0"
   },
   "autoload": {