[skip CI] i18n: Translate deepin-custom-screensaver.ts in pl

92% of minimum 1% translated source file: 'deepin-custom-screensaver.ts'
on 'pl'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

Author: transifex-integration[bot]

customscreensaver/deepin-custom-screensaver/translations/deepin-custom-screensaver_pl.ts

@@ -28,7 +28,7 @@
     <message>
         <location filename="../src/config/selectpathwidget.cpp" line="83"/>
         <source>Select a valid image path</source>
-        <translation type="unfinished"/>
+        <translation>Wybierz prawidłową ścieżkę obrazu</translation>
     </message>
 </context>
 <context>
@@ -51,7 +51,7 @@
     <message>
         <location filename="../src/slideshowconfigdialog.cpp" line="135"/>
         <source>Slideshow</source>
-        <translation type="unfinished"/>
+        <translation>Pokaz slajdów</translation>
     </message>
     <message>
         <location filename="../src/slideshowconfigdialog.cpp" line="228"/>