fix: update Node.js version suitable for dev development and improve Dockerfile syntax

dev/containers/Dockerfile

@@ -1,17 +1,20 @@
 # -- DEV DOCKERFILE --
 # -- DO NOT USE IN PRODUCTION! --
 
-FROM node:18
-LABEL maintainer "requarks.io"
+FROM node:20
+LABEL maintainer="requarks.io"
 
 RUN apt-get update && \
-    apt-get install -y bash curl git python3 make g++ nano openssh-server gnupg && \
+    apt-get install -y --no-install-recommends bash curl git python3 make g++ nano openssh-server gnupg && \
+    apt-get upgrade -y && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/* && \
     mkdir -p /wiki
 
 WORKDIR /wiki
 
-ENV dockerdev 1
-ENV DEVDB postgres
+ENV dockerdev=1
+ENV DEVDB=postgres
 
 EXPOSE 3000