Remove circular requirement of testing suite

The testing suite requires this package which causes problems with
updates. This package now requires most dependencies of the testing
suite by itself.

composer.json

@@ -9,7 +9,6 @@
             "email": "[email protected]"
         }
     ],
-    "version": "2.1.0",
     "require": {
         "php": "^7.1",
         "composer-plugin-api": "^1.0 || ^2.0"
@@ -18,7 +17,10 @@
         "phpunit/phpunit": "^7.5",
         "composer/composer": "^1.3 || ^2.0",
         "kint-php/kint": "@stable",
-        "mediact/testing-suite": "^2.0",
+        "mediact/coding-standard": "@stable",
+        "phpro/grumphp": ">=0.19 <1.0",
+        "phpstan/phpstan": "@stable",
+        "sensiolabs/security-checker": "@stable",
         "mikey179/vfsstream": "^1.6"
     },
     "autoload": {

grumphp.yml

@@ -1,11 +1,96 @@
-imports:
-  - resource: 'vendor/mediact/testing-suite/config/default/grumphp.yml'
-
 parameters:
+  # Default settings for testing suite tasks
   composer.strict: false
+
+  jsonlint.detect_key_conflicts: true
+
+  xmllint.load_from_net: true
+  xmllint.x_include: true
+  xmllint.dtd_validation: true
+  xmllint.scheme_validation: true
+  xmllint.triggered_by: [xml]
   xmllint.ignore_patterns:
     # Uses an incomplete definition, which conflicts when <exclude-pattern>
     # is defined.
     - /^phpcs.xml$/
     - /^phpmd.xml$/
-    - '#^files/.*\.xml$#'
+    - /^phpunit.xml$/
+    - /^pdepend.xml$/
+    - /^files/
+
+  yamllint.parse_constant: true
+
+  phpcs.standard: ./phpcs.xml
+  phpcs.triggered_by: [php]
+
+  phpmd.exclude: []
+  phpmd.ruleset:
+    - ./phpmd.xml
+  phpmd.triggered_by: [php]
+
+  phpstan.autoload_file: ~
+  phpstan.configuration: ./phpstan.neon
+  phpstan.level: 4
+  phpstan.triggered_by: [php]
+
+  phpunit.config_file: ./phpunit.xml
+
+  securitychecker.lockfile: ./composer.lock
+  securitychecker.format: ~
+  securitychecker.end_point: ~
+  securitychecker.timeout: ~
+  securitychecker.run_always: true
+
+grumphp:
+
+  ascii:
+    failed: ~
+    succeeded: ~
+
+  parallel:
+    enabled: false
+
+  # Default tasks for testing suite
+  tasks:
+    composer:
+      strict: '%composer.strict%'
+
+    jsonlint:
+      detect_key_conflicts: '%jsonlint.detect_key_conflicts%'
+
+    xmllint:
+      load_from_net: '%xmllint.load_from_net%'
+      x_include: '%xmllint.x_include%'
+      dtd_validation: '%xmllint.dtd_validation%'
+      scheme_validation: '%xmllint.scheme_validation%'
+      triggered_by: '%xmllint.triggered_by%'
+      ignore_patterns: '%xmllint.ignore_patterns%'
+
+    yamllint:
+      parse_constant: '%yamllint.parse_constant%'
+
+    phpcs:
+      standard: '%phpcs.standard%'
+      triggered_by: '%phpcs.triggered_by%'
+
+    phpmd:
+      exclude: '%phpmd.exclude%'
+      ruleset: '%phpmd.ruleset%'
+      triggered_by: '%phpmd.triggered_by%'
+
+    phpstan:
+      autoload_file: '%phpstan.autoload_file%'
+      configuration: '%phpstan.configuration%'
+      level: '%phpstan.level%'
+      triggered_by: '%phpstan.triggered_by%'
+
+    phpunit:
+      config_file: '%phpunit.config_file%'
+
+    securitychecker:
+      lockfile: '%securitychecker.lockfile%'
+      format: '%securitychecker.format%'
+      end_point: '%securitychecker.end_point%'
+      timeout: '%securitychecker.timeout%'
+      run_always: '%securitychecker.run_always%'
+