Fix playlist shuffle, index upper bound off-by-one

This caused projectM to sometimes stop switching presets if the index chosen was the end of the given interval. Since the preset switch fails in this case, no additional switches will happen unless the user manually switches to a new preset.

Signed-off-by: Kai Blaschke <kai.blaschke@kb-dev.net>

Author: kblaschke

src/playlist/Playlist.cpp

@@ -253,7 +253,7 @@ auto Playlist::NextPresetIndex() -> uint32_t
 
     if (m_shuffle)
     {
-        std::uniform_int_distribution<uint32_t> randomDistribution(0, static_cast<uint32_t>(m_items.size()));
+        std::uniform_int_distribution<uint32_t> randomDistribution(0, static_cast<uint32_t>(m_items.size() - 1));
         m_currentPosition = randomDistribution(m_randomGenerator);
     }
     else
@@ -280,7 +280,7 @@ auto Playlist::PreviousPresetIndex() -> uint32_t
 
     if (m_shuffle)
     {
-        std::uniform_int_distribution<uint32_t> randomDistribution(0, static_cast<uint32_t>(m_items.size()));
+        std::uniform_int_distribution<uint32_t> randomDistribution(0, static_cast<uint32_t>(m_items.size() - 1));
         m_currentPosition = randomDistribution(m_randomGenerator);
     }
     else