Fix debian/ubuntu arm64 build error,runtime argument missing

[FantasyGmm]

I tried to compile on Rock 5B, but it`s fail

log:

make[1]: Entering directory '/root/jellyfin'
dotnet publish -maxcpucount:1 --configuration Release --output='/root/jellyfin/usr/lib/jellyfin/bin' --self-contained --runtime  \
        -p:DebugSymbols=false -p:DebugType=none Jellyfin.Server
Required argument missing for option: --runtime

I checked the build script and found that it used arch to obtain the architecture. However, on the Armbian system, he returned aarch64 instead of the existing arm64 in the script, which resulted in the runtime missing parameters

root@rock-5b:~/jellyfin# arch
aarch64
root@rock-5b:~/jellyfin# neofetch
                                 root@rock-5b
                                 ------------
      █ █ █ █ █ █ █ █ █ █ █      OS: Armbian (23.08.0-trunk) aarch64
     ███████████████████████     Host: Radxa ROCK 5B
   ▄▄██                   ██▄▄   Kernel: 5.10.160-legacy-rk35xx
   ▄▄██    ███████████    ██▄▄   Uptime: 2 hours, 27 mins
   ▄▄██   ██         ██   ██▄▄   Packages: 1444 (dpkg)
   ▄▄██   ██         ██   ██▄▄   Shell: bash 5.1.16
   ▄▄██   ██         ██   ██▄▄   Terminal: /dev/pts/0
   ▄▄██   █████████████   ██▄▄   CPU: (8) @ 1.800GHz
   ▄▄██   ██         ██   ██▄▄   Memory: 1695MiB / 7688MiB
   ▄▄██   ██         ██   ██▄▄
   ▄▄██   ██         ██   ██▄▄
   ▄▄██                   ██▄▄
     ███████████████████████
      █ █ █ █ █ █ █ █ █ █ █

Changes
I added the judgment for aarch64 in the debian/rules file