minor symfony#20445 Fix typo (dearaujoj)

This PR was submitted for the 7.2 branch but it was merged into the 6.4 branch instead.

Discussion
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Fix typo

"seperate" should be "separate" in the text: "the process in two seperate responsibilities"

#SymfonyHackday

Commits
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38b721e Fix typo

Author: javiereguiluz

serializer.rst

@@ -238,7 +238,7 @@ The serializer uses a two-step process when (de)serializing objects:
     ></object>
 
 In both directions, data is always first converted to an array. This splits
-the process in two seperate responsibilities:
+the process in two separate responsibilities:
 
 Normalizers
     These classes convert **objects** into **arrays** and vice versa. They