docker: migrate to new nodesource repo; node 19 -> 20

old node setup script had a warning to migrate with 60s pause during docker build

https://github.com/nodesource/distributions/wiki/How-to-migrate-to-the-new-repository

Dockerfile

@@ -10,8 +10,11 @@ ARG DEBIAN_FRONTEND=noninteractive
 
 # Install up-to-date node & npm, deps for virtual screen & noVNC, firefox, pip for apprise.
 RUN apt-get update \
-    && apt-get install --no-install-recommends -y curl ca-certificates \
-    && curl -fsSL https://deb.nodesource.com/setup_19.x | bash - \
+    && apt-get install --no-install-recommends -y curl ca-certificates gnupg \
+    && mkdir -p /etc/apt/keyrings \
+    && curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg \
+    && echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_20.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list \
+    && apt-get update \
     && apt-get install --no-install-recommends -y \
       nodejs \
       xvfb \
@@ -42,6 +45,9 @@ RUN apt-get update \
       /var/lib/apt/lists/* \
       /var/tmp/*
 
+# RUN node --version
+# RUN npm --version
+
 RUN ln -s /usr/share/novnc/vnc_auto.html /usr/share/novnc/index.html
 RUN pip install apprise