bug #6717 Cache Component: Fix SQLite3Cache instanciation (ReDnAxE)

This PR was merged into the 3.1 branch.

Discussion
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Cache Component: Fix SQLite3Cache instanciation

My first small contribution ^^
`new SQLite3Cache()` instead of `new SQLite3()` according to the use statement

Commits
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faa3447 Cache Component: Fix SQLite3Cache instanciation

Author: wouterj

components/cache/cache_pools.rst

@@ -153,7 +153,7 @@ application as if they were Symfony Cache adapters::
     use Doctrine\Common\Cache\SQLite3Cache;
     use Symfony\Component\Cache\Adapter\DoctrineAdapter;
 
-    $doctrineCache = new SQLite3(__DIR__.'/cache/data.sqlite');
+    $doctrineCache = new SQLite3Cache(__DIR__.'/cache/data.sqlite');
     $symfonyCache = new DoctrineAdapter($doctrineCache);
 
 This adapter also defines two optional arguments called  ``namespace`` (default: