Typing does not work in serial built-in terminal on macOS 27 Public Beta

**Describe the issue**
When using a serial device with the mode Built-In Terminal typing does not work. This happened after upgrading from macOS 26 to macOS 27 Public Beta 2

I checked it with two different Linux-VMs and both had the issue.

**Configuration**
* UTM Version: Version 5.0.4 (123) (AppStore)
* macOS Version: 27.0 Beta (26A5388g)
* Mac Chip (Intel, M1, ...): M3

**Debug log**
```
Launching: qemu-system-aarch64 -L /Users/nik/Library/Containers/com.utmapp.UTM/Data/Library/Caches/qemu -S -spice unix=on,addr=DE71F851-FA85-4958-96BC-3812EBE8CB4C.spice,disable-ticketing=on,image-compression=off,playback-compression=off,streaming-video=off,gl=core -chardev spiceport,name=org.qemu.monitor.qmp.0,id=org.qemu.monitor.qmp -mon chardev=org.qemu.monitor.qmp,mode=control -nodefaults -vga none -device virtio-net-pci,mac=FE:9C:21:F2:21:A9,netdev=net0 -netdev vmnet-shared,id=net0 -device virtio-gpu-gl-pci -chardev spiceport,id=term0,name=com.utmapp.terminal.0 -serial chardev:term0 -cpu host -smp cpus=4,sockets=1,cores=4,threads=1 -machine virt -accel hvf -drive if=pflash,format=raw,unit=0,file.filename=/Users/nik/Library/Containers/com.utmapp.UTM/Data/Library/Caches/qemu/edk2-aarch64-code.fd,file.locking=off,readonly=on -drive if=pflash,unit=1,file.filename=/Users/nik/Library/Containers/com.utmapp.UTM/Data/Documents/snafu.utm/Data/efi_vars.fd -m 6144 -audiodev spice,id=audio0 -device intel-hda -device hda-duplex,audiodev=audio0 -device nec-usb-xhci,id=usb-bus -device usb-tablet,bus=usb-bus.0 -device usb-mouse,bus=usb-bus.0 -device usb-kbd,bus=usb-bus.0 -device qemu-xhci,id=usb-controller-0 -chardev spicevmc,name=usbredir,id=usbredirchardev0 -device usb-redir,chardev=usbredirchardev0,id=usbredirdev0,bus=usb-controller-0.0 -chardev spicevmc,name=usbredir,id=usbredirchardev1 -device usb-redir,chardev=usbredirchardev1,id=usbredirdev1,bus=usb-controller-0.0 -chardev spicevmc,name=usbredir,id=usbredirchardev2 -device usb-redir,chardev=usbredirchardev2,id=usbredirdev2,bus=usb-controller-0.0 -device virtio-blk-pci,drive=drive5472637D-3AF2-43C3-B347-BC17912C90DB,serial=5472637D3AF243C3B347,bootindex=0 -drive if=none,media=disk,id=drive5472637D-3AF2-43C3-B347-BC17912C90DB,file.filename=/Users/nik/Library/Containers/com.utmapp.UTM/Data/Documents/snafu.utm/Data/5472637D-3AF2-43C3-B347-BC17912C90DB.qcow2,discard=unmap,detect-zeroes=unmap -device virtio-serial -device virtserialport,chardev=org.qemu.guest_agent,name=org.qemu.guest_agent.0 -chardev spiceport,name=org.qemu.guest_agent.0,id=org.qemu.guest_agent -device virtserialport,chardev=vdagent,name=com.redhat.spice.0 -chardev spicevmc,id=vdagent,debug=0,name=vdagent -name snafu -uuid DE71F851-FA85-4958-96BC-3812EBE8CB4C -device virtio-rng-pci
Environment variables:
NPT_D3D11_LIBRARY_PATH=/Applications/UTM.app/Contents/Frameworks/dxmt-native.framework/Versions/A/dxmt-native
MTL_DEBUG_LAYER=1
NPT_BACKEND=dxmt
NPT_DXGI_LIBRARY_PATH=/Applications/UTM.app/Contents/Frameworks/dxmt-native.framework/Versions/A/dxmt-native
MTL_DEBUG_LAYER_ERROR_MODE=nslog
APP_SANDBOX_GROUP_ID=WDNLXAD4W8.com.utmapp.UTM
VIRGL_LOG_LEVEL=debug
XDG_RUNTIME_DIR=/Users/nik/Library/Group Containers/WDNLXAD4W8.com.utmapp.UTM
NPT_D3D12_LIBRARY_PATH=/Applications/UTM.app/Contents/Frameworks/dxmt-native.framework/Versions/A/dxmt-native
ANGLE_METAL_DEBUG_BINDINGS=1
MVK_CONFIG_LOG_LEVEL=4
VK_LOADER_DEBUG=all
MVK_DEBUG=1
G_MESSAGES_DEBUG=all
ANGLE_ENABLE_DEBUG_TRACE=1
MESA_DEBUG=1
```

Reproduce the issue using UTM 5.0.4 on macOS 27 with a serial device in Built-In Terminal, comparing typing behavior before and after the OS upgrade. Start from the serial terminal path indicated by the qemu-system-aarch64 debug command and its SPICE chardev, and consider the issue done when typing works again in both Linux VMs.

Written by the indexing model from the issue text.