Core/Misc: Fix some -Wconversion warnings

src/server/game/Entities/Unit/StatSystem.cpp

@@ -878,7 +878,7 @@ void Player::UpdateManaRegen()
 {
     float Intellect = GetStat(STAT_INTELLECT);
     // Mana regen from spirit and intellect
-    float power_regen = sqrt(Intellect) * OCTRegenMPPerSpirit();
+    float power_regen = std::sqrt(Intellect) * OCTRegenMPPerSpirit();
     // Apply PCT bonus from SPELL_AURA_MOD_POWER_REGEN_PERCENT aura on spirit base regen
     power_regen *= GetTotalAuraMultiplierByMiscValue(SPELL_AURA_MOD_POWER_REGEN_PERCENT, POWER_MANA);