Bump symfony/yaml from 4.4.11 to 4.4.12

Bumps [symfony/yaml](https://github.com/symfony/yaml) from 4.4.11 to 4.4.12.
- [Release notes](https://github.com/symfony/yaml/releases)
- [Changelog](https://github.com/symfony/yaml/blob/master/CHANGELOG.md)
- [Commits](https://github.com/symfony/yaml/compare/v4.4.11...v4.4.12)

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

composer.json

@@ -54,7 +54,7 @@
         "doctrine/instantiator": "^1.1",
         "phpdocumentor/reflection-docblock": "5.2.1",
         "symfony/debug": "4.4.11",
-        "symfony/yaml": "4.4.11",
+        "symfony/yaml": "4.4.12",
         "symfony/finder": "3.4.8",
         "symfony/stopwatch" : "4.4.11",
         "myclabs/deep-copy": "1.10.1",