폰트 이름 변경

pretendard_bold -> bold
pretendard_regular -> regular
pretendard_medium -> medium
pretendard_light -> light

app/src/main/res/layout/fragment_chat_background_picker.xml

@@ -30,7 +30,7 @@
             android:layout_marginStart="12dp"
             android:layout_weight="1"
             android:ellipsize="end"
-            android:fontFamily="@font/pretendard_bold"
+            android:fontFamily="@font/bold"
             android:maxLines="1"
             android:text="@string/chat_background_picker_title"
             android:textColor="#FFFFFFFF"