Run CSSTidy tests on CI (#338)

* Run CSSTidy tests on CI

* update dirname

* use compopser instead of git clone

* use composer

* use test-settings.sample.php

* enable ext-intl

* disable Net_IDNA2

composer.json

@@ -15,6 +15,10 @@
     "require": {
         "php": "~5.6.0 || ~7.0.0 || ~7.1.0 || ~7.2.0 || ~7.3.0 || ~7.4.0 || ~8.0.0 || ~8.1.0 || ~8.2.0"
     },
+    "require-dev": {
+        "cerdic/css-tidy": "^1.7 || ^2.0",
+        "simpletest/simpletest": "dev-master"
+    },
     "autoload": {
         "psr-0": { "HTMLPurifier": "library/" },
         "files": ["library/HTMLPurifier.composer.php"],
@@ -27,5 +31,14 @@
         "ext-iconv": "Converts text to and from non-UTF-8 encodings",
         "ext-bcmath": "Used for unit conversion and imagecrash protection",
         "ext-tidy": "Used for pretty-printing HTML"
-    }
+    },
+    "config": {
+        "sort-packages": true
+    },
+    "repositories": [
+        {
+            "type": "vcs",
+            "url": "https://github.com/ezyang/simpletest.git"
+        }
+    ]
 }