bug symfony#28783 [FrameworkBundle] add missing cache prefix seed attribute to XSD (xabbuh)

This PR was merged into the 3.4 branch.

Discussion
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[FrameworkBundle] add missing cache prefix seed attribute to XSD

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
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03dbd84 add missing cache prefix seed attribute to XSD

Author: fabpot

src/Symfony/Bundle/FrameworkBundle/Resources/config/schema/symfony-1.0.xsd

@@ -249,6 +249,8 @@
             <xsd:element name="default-memcached-provider" type="xsd:string" minOccurs="0" maxOccurs="1" />
             <xsd:element name="pool" type="cache_pool" minOccurs="0" maxOccurs="unbounded" />
         </xsd:sequence>
+
+        <xsd:attribute name="prefix-seed" type="xsd:string" />
     </xsd:complexType>
 
     <xsd:complexType name="cache_pool">