PHP 7.3 and fix Symfony repositories to 4.2.*

Author: steevanb

composer.json

@@ -33,20 +33,25 @@
         "symfony/polyfill-php70": "*",
         "symfony/polyfill-php56": "*"
     },
-    "scripts": {
-        "auto-scripts": {
-            "cache:clear": "symfony-cmd",
-            "assets:install %PUBLIC_DIR%": "symfony-cmd"
-        },
-        "post-install-cmd": [
-            "@auto-scripts"
-        ],
-        "post-update-cmd": [
-            "@auto-scripts"
-        ]
-    },
     "conflict": {
-        "symfony/symfony": "*"
+        "symfony/symfony": "*",
+        "https://github.com/composer/composer/issues/7827": "0.0.0",
+        "https://github.com/symfony/symfony/issues/29581": "0.0.0",
+        "symfony/routing": ">=4.3.0",
+        "symfony/http-foundation": ">=4.3.0",
+        "symfony/event-dispatcher": ">=4.3.0",
+        "symfony/debug": ">=4.3.0",
+        "symfony/http-kernel": ">=4.3.0",
+        "symfony/finder": ">=4.3.0",
+        "symfony/filesystem": ">=4.3.0",
+        "symfony/dependency-injection": ">=4.3.0",
+        "symfony/config": ">=4.3.0",
+        "symfony/var-exporter": ">=4.3.0",
+        "symfony/cache": ">=4.3.0",
+        "symfony/serializer": ">=4.3.0",
+        "symfony/inflector": ">=4.3.0",
+        "symfony/property-info": ">=4.3.0",
+        "symfony/property-access": ">=4.3.0"
     },
     "extra": {
         "symfony": {