minor #41895 update Italian translation (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
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update Italian translation

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | none
| License       | MIT
| Doc PR        | unneeded

Add missing translation for Italian language.

Commits
-------

18bf1bf update Italian translation

src/Symfony/Component/Validator/Resources/translations/validators.it.xlf

@@ -386,6 +386,10 @@
                 <source>This value is not a valid International Securities Identification Number (ISIN).</source>
                 <target>Questo valore non è un codice identificativo internazionale di valori mobiliari (ISIN) valido.</target>
             </trans-unit>
+            <trans-unit id="100">
+                <source>This value should be a valid expression.</source>
+                <target>Questo valore dovrebbe essere un'espressione valida.</target>
+            </trans-unit>
         </body>
     </file>
 </xliff>