added phpstan config with baseline

Author: connorhu

composer.json

@@ -26,6 +26,9 @@
         "ext-pdo": "*",
         "ext-zlib": "*"
     },
+    "require-dev": {
+        "phpstan/phpstan": "^1.10"
+    },
     "support": {
         "issues": "https://github.com/FriendsOfSymfony1/doctrine1/issues",
         "source": "https://github.com/FriendsOfSymfony1/doctrine1"
@@ -42,5 +45,11 @@
     },
     "config": {
         "sort-packages": true
+    },
+    "scripts": {
+        "analyse": [
+            "@phpstan"
+        ],
+        "phpstan": "phpstan analyse --memory-limit 1G"
     }
 }