Update Composer dependencies (2020-04-14)

[danielbachhuber]

Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 0 installs, 18 updates, 1 removal
  - Removing symfony/class-loader (v3.3.6)
  - Updating squizlabs/php_codesniffer (3.4.2 => 3.5.4): Loading from cache
  - Updating wp-coding-standards/wpcs (2.1.1 => 2.2.1): Loading from cache
  - Updating sebastian/exporter (3.1.1 => 3.1.2): Loading from cache
  - Updating symfony/polyfill-ctype (v1.12.0 => v1.15.0): Loading from cache
  - Updating webmozart/assert (1.4.0 => 1.7.0): Loading from cache
  - Updating phpdocumentor/type-resolver (0.4.0 => 0.5.1): Downloading (100%)
  - Updating phpdocumentor/reflection-docblock (4.3.1 => 4.3.4): Loading from cache
  - Updating phpspec/prophecy (1.8.1 => v1.10.3): Loading from cache
  - Updating phpcompatibility/php-compatibility (9.3.2 => 9.3.5): Loading from cache
  - Updating symfony/polyfill-mbstring (v1.12.0 => v1.15.0): Loading from cache
  - Updating psr/log (1.1.0 => 1.1.3): Loading from cache
  - Updating symfony/console (v2.8.50 => v2.8.52): Loading from cache
  - Updating behat/transliterator (v1.2.0 => v1.3.0): Loading from cache
  - Updating behat/gherkin (v4.6.0 => v4.6.2): Loading from cache
  - Updating behat/behat (v3.5.0 => v3.6.1): Loading from cache
  - Updating behat/mink (v1.7.1 => v1.8.1): Loading from cache
  - Updating behat/mink-browserkit-driver (1.3.3 => v1.3.4): Loading from cache
  - Updating guzzlehttp/guzzle (6.3.3 => 6.5.2): Loading from cache