Fatal error after upgrade to 0.11.4

Q	A
Version	`0.11.4`
Bug?	yes
New feature?	no
Question?	no
Documentation?	no
Related tickets

GrumPHP start throwing an error after upgrading to 0.11.4

PHP Fatal error:  Uncaught TypeError: Argument 2 passed to GrumPHP\Task\AbstractExternalTask::__construct() must be an instance of GrumPHP\Pr
ocess\ProcessBuilder, none given in /vendor/phpro/grumphp/src/Task/AbstractExternalTas
k.php:31

My configuration

# grumphp.yml
parameters:
  bin_dir: "./vendor/bin"
  git_dir: "."
  stop_on_failure: true
  process_async_limit: 20
  process_async_wait: 1000
  process_timeout: 60
  ascii:
    failed: grumphp-grumpy.txt
    succeeded: grumphp-happy.txt
  tasks:
    composer: ~
    git_blacklist:
      keywords:
        - "die("
        - "var_dump("
        - "exit;"
      triggered_by: [php]
    git_conflict: ~
    jsonlint: ~
#    phpcpd:
#      directory: '.'
#      exclude: ['vendor']
#      names_exclude: []
#      fuzzy: false
#      min_lines: 5
#      min_tokens: 70
#      triggered_by: ['php']
#    phpcs:
#      whitelist_patterns:
#        - /^app\/(.*)/
#      ignore_patterns:
#        - /^tests\/(.*)/
#        - /^database\/(.*)/
#        - /^storage\/(.*)/
#        - /^resources\/(.*)/
#        - /^*.routes.php/
#      standard: 'PSR2'
#      show_warnings: true
#      tab_width: 4
#      triggered_by: [php]
    phplint: ~
#    phpmd: ~
    phpparser: ~
    phpunit: ~
    phpversion: ~
    securitychecker: ~
    shell: ~
    yamllint: ~
    phpcsfixer:
      config_file: './.php_cs'
      fixers:
        - blankline_after_open_tag
        - braces
        - concat_without_spaces
        - double_arrow_multiline_whitespaces
        - duplicate_semicolon
        - elseif
        - empty_return
        - encoding
        - eof_ending
        - extra_empty_lines
        - function_call_space
        - function_declaration
        - include
        - indentation
        - join_function
        - line_after_namespace
        - linefeed
        - list_commas
        - logical_not_operators_with_successor_space
        - lowercase_constants
        - lowercase_keywords
        - method_argument_space
        - multiline_array_trailing_comma
        - multiline_spaces_before_semicolon
        - multiple_use
        - namespace_no_leading_whitespace
        - no_blank_lines_after_class_opening
        - no_empty_lines_after_phpdocs
        - object_operator
        - operators_spaces
        - parenthesis
        - phpdoc_indent
        - phpdoc_inline_tag
        - phpdoc_no_access
        - phpdoc_no_package
        - phpdoc_scalar
        - phpdoc_short_description
        - phpdoc_to_comment
        - phpdoc_trim
        - phpdoc_type_to_var
        - phpdoc_var_without_name
        - remove_leading_slash_use
        - remove_lines_between_uses
        - return
        - self_accessor
        - short_array_syntax
        - short_echo_tag
        - short_tag
        - single_array_no_trailing_comma
        - single_blank_line_before_namespace
        - single_line_after_imports
        - single_quote
        - spaces_before_semicolon
        - spaces_cast
        - standardize_not_equal
        - ternary_spaces
        - trailing_spaces
        - trim_array_spaces
        - unalign_equals
        - unary_operators_spaces
        - unused_use
        - visibility
        - whitespacy_lines
  testsuites: []
  extensions: []

Steps to reproduce:

# Generate empty folder
mkdir tmp
cd tmp
git init
echo "vendor" > .gitignore
pbpaste > grumphp.yml
composer require --dev phpro/grumphp

# Your actions
# Please add the steps on how to reproduce the issue here.

# Run GrumpHP:
git add -A && git commit -m"Test"
# or
./vendor/bin/grumphp run

Result:

PHP Fatal error:  Uncaught TypeError: Argument 2 passed to GrumPHP\Task\AbstractExternalTask::__construct() must be an instance of GrumPHP\Pr
ocess\ProcessBuilder, none given in /vendor/phpro/grumphp/src/Task/AbstractExternalTas
k.php:31

phpro / grumphp

Fatal error after upgrade to 0.11.4 #351