mv spatie/symfony-ignition-bundle/0.0/config/packages{,/dev}/ignition.yaml (symfony#1689)

* fix `There is no extension able to load the configuration for "ignition" (in "config/packages/ignition.yaml"). Looked for namespace "ignition", found "framework", "doctrine", "twig".` when under environments other than `dev`

* fix symfony#1689 (review)

Author: n0099

spatie/symfony-ignition-bundle/0.0/config/packages/ignition.yaml

@@ -1,2 +1,3 @@
-ignition:
-    dark_mode: false
+when@dev:
+    ignition:
+        dark_mode: false