Do not rely on the current locale when dumping a Graphviz object
Do not rely on the current locale when dumping a Graphviz object

Funny bug !

With `de_DE.UTF-8` as locale:
```
php > echo sprintf('%s', 0.5);
0,5
php > echo sprintf('%d', 0.5);
0
php > echo sprintf('%f', 0.5);
0,500000
php > echo (string) 0.5;
0,5
```

So now we force `'0.5'`

symfony/dependency-injection