minor symfony#17811 [FrameworkBundle] fix YAML syntax (xabbuh)

This PR was merged into the 2.7 branch.

Discussion
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[FrameworkBundle] fix YAML syntax

| Q             | A
| ------------- | ---
| Fixed tickets |
| License       | MIT

see failing tests in symfony#17809

Commits
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2da4038 [FrameworkBundle] fix YAML syntax

Author: fabpot

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/yml/assets.yml

@@ -1,7 +1,7 @@
 framework:
     assets:
         version: SomeVersionScheme
-        version_format: %%s?version=%%s
+        version_format: '%%s?version=%%s'
         base_urls: http://cdn.example.com
         packages:
             images_path:
@@ -11,7 +11,7 @@ framework:
                 base_urls: ["http://images1.example.com", "http://images2.example.com"]
             foo:
                 version: 1.0.0
-                version_format: %%s-%%s
+                version_format: '%%s-%%s'
             bar:
                 base_urls: ["https://bar2.example.com"]
             bar_null_version: