Merge pull request #2249 from Narfinger/docker-fix

fixes dockerfile building on recent linux installations

Dockerfile

@@ -14,7 +14,9 @@ FROM mcr.microsoft.com/dotnet/core/sdk:${DOTNET_VERSION}-buster as builder
 WORKDIR /repo
 COPY . .
 ENV DOTNET_CLI_TELEMETRY_OPTOUT=1
-RUN dotnet publish Jellyfin.Server --configuration Release --output="/jellyfin" --self-contained --runtime linux-x64 "-p:GenerateDocumentationFile=false;DebugSymbols=false;DebugType=none"
+# because of changes in docker and systemd we need to not build in parallel at the moment
+# see https://success.docker.com/article/how-to-reserve-resource-temporarily-unavailable-errors-due-to-tasksmax-setting
+RUN dotnet publish Jellyfin.Server --disable-parallel --configuration Release --output="/jellyfin" --self-contained --runtime linux-x64 "-p:GenerateDocumentationFile=false;DebugSymbols=false;DebugType=none"
 
 FROM jellyfin/ffmpeg:${FFMPEG_VERSION} as ffmpeg
 FROM debian:buster-slim