Update symfony/yaml requirement from ^7.0 to ^8.0

[dependabot]

Updates the requirements on symfony/yaml to permit the latest version.

Release notes

Sourced from symfony/yaml's releases.

v8.0.8

Changelog (symfony/yaml@v8.0.7...v8.0.8)

• no significant changes

Changelog

Sourced from symfony/yaml's changelog.

CHANGELOG

8.0

• Remove support for parsing duplicate mapping keys whose value is null

7.3

• Add compact nested mapping support by using the Yaml::DUMP_COMPACT_NESTED_MAPPING flag
• Add the Yaml::DUMP_FORCE_DOUBLE_QUOTES_ON_VALUES flag to enforce double quotes around string values

7.2

• Deprecate parsing duplicate mapping keys whose value is null
• Add support for dumping null as an empty value by using the Yaml::DUMP_NULL_AS_EMPTY flag

7.1

• Add support for getting all the enum cases with !php/enum Foo

7.0

• Remove the !php/const: tag, use !php/const instead (without the colon)

6.3

• Add support to dump int keys as strings by using the Yaml::DUMP_NUMERIC_KEY_AS_STRING flag

6.2

• Add support for !php/enum and !php/enum *->value
• Deprecate the !php/const: tag in key which will be replaced by the !php/const tag (without the colon) since 3.4

6.1

• In cases where it will likely improve readability, strings containing single quotes will be double-quoted

5.4

• Add new lint:yaml dirname --exclude=/dirname/foo.yaml --exclude=/dirname/bar.yaml

... (truncated)

Commits

• 54174ab Merge branch '7.4' into 8.0
• c58fdf7 Configure deprecation triggers
• 5f006c5 Merge branch '7.4' into 8.0
• 5875104 Merge branch '6.4' into 7.4
• 7bca30d [Yaml] Fix parsing nested mappings in sequences
• 7a1a90b Merge branch '7.4' into 8.0
• 24dd4de Merge branch '7.3' into 7.4
• 8892cb1 Merge branch '6.4' into 7.3
• 8207ae8 [Yaml] Fix regression handling blank lines in unquoted scalars
• 74521d9 Merge branch '7.4' into 8.0
• Additional commits viewable in compare view

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