adapted text color (#2447)

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>

Corona-Warn-App/src/main/res/color/button_text_color_emphasized.xml

 <?xml version="1.0" encoding="utf-8"?>
 <selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:color="@color/colorBackground" android:state_enabled="false" /> <!-- disabled -->
+    <item android:color="@color/colorTextPrimary3" android:state_enabled="false" /> <!-- disabled -->
     <item android:color="@color/colorTextEmphasizedButton" /> <!-- default -->
 </selector>
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