Add npminstall to pip and docker build processes

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.8
+FROM python:3.9
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
@@ -31,7 +31,11 @@ RUN apt-get update && \
     useradd -ms /bin/bash -d /pretix -u 15371 pretixuser && \
     echo 'pretixuser ALL=(ALL) NOPASSWD:SETENV: /usr/bin/supervisord' >> /etc/sudoers && \
     mkdir /static && \
-    mkdir /etc/supervisord
+    mkdir /etc/supervisord && \
+	curl -fsSL https://deb.nodesource.com/setup_15.x | sudo -E bash - && \
+    apt-get install -y nodejs && \
+    curl -qL https://www.npmjs.com/install.sh | sh
+
 
 ENV LC_ALL=C.UTF-8 \
     DJANGO_SETTINGS_MODULE=production_settings
@@ -67,7 +71,6 @@ RUN chmod +x /usr/local/bin/pretix && \
     rm -f pretix.cfg && \
 	mkdir -p data && \
     chown -R pretixuser:pretixuser /pretix /data data && \
-	sudo -u pretixuser make npminstall && \
 	sudo -u pretixuser make production
 
 USER pretixuser