Revert FFMpegCore wrapper to 4.7 to avoid random failures

src/NzbDrone.Core/Sonarr.Core.csproj

@@ -6,7 +6,7 @@
     <PackageReference Include="Dapper" Version="2.0.123" />
     <PackageReference Include="MailKit" Version="2.10.1" />
     <PackageReference Include="Microsoft.AspNetCore.Cryptography.KeyDerivation" Version="6.0.6" />
-    <PackageReference Include="Servarr.FFMpegCore" Version="4.8.0-29" />
+    <PackageReference Include="Servarr.FFMpegCore" Version="4.7.0-26" />
     <PackageReference Include="Servarr.FFprobe" Version="5.1.2.106" />
     <PackageReference Include="System.Memory" Version="4.5.4" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="6.0.0" />