Update Dockerfiles to use node:22-slim as the base image

apps/app/docker/Dockerfile

@@ -72,7 +72,7 @@ RUN tar -zcf /tmp/packages.tar.gz \
 ##
 ## release
 ##
-FROM node:20-slim
+FROM node:22-slim
 LABEL maintainer="Yuki Takei <yuki@weseek.co.jp>"
 
 ARG OPT_DIR

apps/pdf-converter/docker/Dockerfile

@@ -63,7 +63,7 @@ RUN tar -zcf /tmp/packages.tar.gz \
 ##
 ## release
 ##
-FROM node:20-slim
+FROM node:22-slim
 LABEL maintainer="Yuki Takei <yuki@weseek.co.jp>"
 
 ARG OPT_DIR

apps/slackbot-proxy/docker/Dockerfile

@@ -52,7 +52,7 @@ RUN tar -zcf packages.tar.gz \
 ##
 ## release
 ##
-FROM node:20-slim
+FROM node:22-slim
 LABEL maintainer="Yuki Takei <yuki@weseek.co.jp>"
 
 ENV NODE_ENV="production"