minor #10454 Updated class reference in Callback validator from the deprecated to the current class. (snebes)

This PR was merged into the 2.8 branch.

Discussion
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Updated class reference in Callback validator from the deprecated to the current class.

This updates the class reference in the documentation for `ExecutionContextInterface` on the `Callback` validator.

This actually affects the documentation from v2.5 to master

Commits
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fc4d5b9 Update Callback.rst

Author: javiereguiluz

reference/constraints/Callback.rst

@@ -298,7 +298,7 @@ Concrete callbacks receive an :class:`Symfony\\Component\\Validator\\Context\\Ex
 instance as only argument.
 
 Static or closure callbacks receive the validated object as the first argument
-and the :class:`Symfony\\Component\\Validator\\ExecutionContextInterface`
+and the :class:`Symfony\\Component\\Validator\\Context\\ExecutionContextInterface`
 instance as the second argument.
 
 .. include:: /reference/constraints/_payload-option.rst.inc