Migrate to .NET 9

src/Ryujinx.Common/PreciseSleep/NanosleepPool.cs

@@ -124,7 +124,7 @@ namespace Ryujinx.Common.PreciseSleep
             }
         }
 
-        private readonly object _lock = new();
+        private readonly Lock _lock = new();
         private readonly List<NanosleepThread> _threads = new();
         private readonly List<NanosleepThread> _active = new();
         private readonly Stack<NanosleepThread> _free = new();

src/Ryujinx.Common/PreciseSleep/WindowsGranularTimer.cs

@@ -50,7 +50,7 @@ namespace Ryujinx.Common.SystemInterop
         private long _lastTicks = PerformanceCounter.ElapsedTicks;
         private long _lastId;
 
-        private readonly object _lock = new();
+        private readonly Lock _lock = new();
         private readonly List<WaitingObject> _waitingObjects = new();
 
         private WindowsGranularTimer()

src/Ryujinx.Common/Ryujinx.Common.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <DefineConstants Condition=" '$(ExtraDefineConstants)' != '' ">$(DefineConstants);$(ExtraDefineConstants)</DefineConstants>
   </PropertyGroup>