add missing german translation

Resources/translations/SonataAdminBundle.de.xliff

@@ -238,6 +238,10 @@
                 <source>label_filters</source>
                 <target>Filter</target>
             </trans-unit>
+            <trans-unit id="label_date_type_equal">
+                <source>label_date_type_equal</source>
+                <target>=</target>
+            </trans-unit>
             <trans-unit id="label_date_type_greater_equal">
               <source>label_date_type_greater_equal</source>
               <target>&gt;=</target>