enable JSON_PRESERVE_ZERO_FRACTION by default

this makes json output float values that happen to be full numbers with a `.0`, so `4.0` or `0.0` instead of `4` resp `0`. that in turn helps when consuming the json in a type-safe language.

Author: dbu

Encoder/JsonEncode.php

@@ -23,7 +23,7 @@ class JsonEncode implements EncoderInterface
     public const OPTIONS = 'json_encode_options';
 
     private $defaultContext = [
-        self::OPTIONS => 0,
+        self::OPTIONS => \JSON_PRESERVE_ZERO_FRACTION,
     ];
 
     public function __construct(array $defaultContext = [])