Update PHPCompatibility

Comment out installed_paths config to fix error:

    $ ./tests/check_coding_standards.sh
    PHP_CodeSniffer version 3.7.1 (stable) by Squiz (http://www.squiz.net)
    ERROR: Referenced sniff "PHPCS23Utils" does not exist

    Run "phpcs --help" for usage information

    Error: found standard violation(s)

composer.json

@@ -19,7 +19,8 @@
     },
     "require-dev": {
         "ext-gd": "*",
-        "phpcompatibility/php-compatibility": "*",
+        "phpcompatibility/php-compatibility": "dev-develop",
+        "phpcsstandards/phpcsutils": "@alpha",
         "phpunit/phpunit": "*",
         "squizlabs/php_codesniffer": "*",
         "vimeo/psalm": "*"

tests/ruleset.xml

@@ -2,7 +2,9 @@
 <ruleset name="PSR2Modified">
     <!-- Run against the PHPCompatibility ruleset. -->
     <rule ref="PHPCompatibility" />
+    <!--
     <config name="installed_paths" value="vendor/phpcompatibility/php-compatibility" />
+    -->
 
     <!-- Run against the PSR2 ruleset with some exclusions. -->
     <rule ref="PSR2">