Update nikic/php-parser requirement from ^3.0 to ^4.2

[dependabot-preview]

Updates the requirements on nikic/php-parser to permit the latest version.

Release notes

Sourced from nikic/php-parser's releases.

PHP-Parser 4.2.1

Added

• [PHP 7.4] Add support for ??= operator through a new AssignOp\Coalesce node. (#575)

Changelog

Sourced from nikic/php-parser's changelog.

Version 4.2.1 (2019-02-16)

Added

• [PHP 7.4] Add support for ??= operator through a new AssignOp\Coalesce node. (#575)

Version 4.2.0 (2019-01-12)

Added

• [PHP 7.4] Add support for typed properties through a new type subnode of Stmt\Property.
  Additionally Builder\Property now has a setType() method. (#567)
• Add kind attribute to Cast\Double_, which allows to distinguish between (float),
  (double) and (real). The form of the cast will be preserved by the pretty printer. (#565)

Fixed

• Remove assertion when pretty printing anonymous class with a name (#554).

Version 4.1.1 (2018-12-26)

Fixed

• Fix "undefined offset" notice when parsing specific malformed code (#551).

Added

• Support error recovery for missing return type (function foo() : {}) (#544).

Version 4.1.0 (2018-10-10)

Added

• Added support for PHP 7.3 flexible heredoc/nowdoc strings, completing support for PHP 7.3. There
  are two caveats for this feature:
  • In some rare, pathological cases flexible heredoc/nowdoc strings change the interpretation of
    existing doc strings. PHP-Parser will now use the new interpretation.
  • Flexible heredoc/nowdoc strings require special support from the lexer. Because this is not
    available on PHP versions before 7.3, support has to be emulated. This emulation is not perfect
    and some cases which we do not expect to occur in practice (such as flexible doc strings being
    nested within each other through abuse of variable-variable interpolation syntax) may not be
    recognized correctly.
• Added DONT_TRAVERSE_CURRENT_AND_CHILDREN to NodeTraverser to skip both traversal of child
  nodes, and prevent subsequent visitors from visiting the current node.

Version 4.0.4 (2018-09-18)

... (truncated)

Commits

• 5221f49 Release PHP-Parser 4.2.1
• ae4e90d Add PHP 7.4 to Travis matrix
• 9de9682 Add support for ??= operator
• b7e6361 updates via "rectorphp/rector" (#573)
• 594bcae Release PHP-Parser 4.2.0
• d5180f0 Change test to use correct node type
• 1f95f92 Tweak type annotation to include null
• 6b9dd7a Avoid redundant argument
• ba09265 Enhancement: Reference phpunit.xsd as installed with composer
• ec0d834 Enhancement: Normalize composer.json
• Additional commits viewable in compare view

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