[static-analysis] Bump PHP stan checks to version 1 passing.

Author: bahiirwa

phpstan.neon

@@ -1,5 +1,5 @@
 parameters:
-    level: 0
+    level: 1
     paths:
         - config.php
         - start.php
@@ -11,4 +11,8 @@ parameters:
     ignoreErrors:
         -
             message: '#will always evaluate to true#'
-            path: includes/class-fs-plugin-updater.php
+            path: includes/class-fs-plugin-updater.php
+        -
+            message: '#Variable \$VARS might not be defined#'
+            paths:
+              - templates/*