Update dockerfile to latest debian bullseye and nginx

Dockerfile

@@ -1,12 +1,11 @@
-FROM debian:stretch
+FROM debian:bullseye
 
 ENV DEBIAN_FRONTEND noninteractive
 
 LABEL Description="This image is used to create an environment to contribute to the cakephp/docs"
 
 RUN apt-get update && apt-get install -y \
     latexmk \
-    openjdk-8-jdk \
     php \
     python3-pip \
     texlive-fonts-recommended \
@@ -19,10 +18,6 @@ RUN apt-get update && apt-get install -y \
 COPY requirements.txt /tmp/
 RUN pip3 install -r /tmp/requirements.txt
 
-ADD https://github.com/w3c/epubcheck/releases/download/v4.2.2/epubcheck-4.2.2.zip /epubcheck/epubcheck.zip
-RUN unzip /epubcheck/epubcheck.zip -d /epubcheck \
-  && mv /epubcheck/epubcheck-4.2.2/* /epubcheck
-
 WORKDIR /data
 VOLUME "/data"
 

deploy.Dockerfile

@@ -1,4 +1,4 @@
-FROM debian:stretch as builder
+FROM debian:bullseye as builder
 
 ENV DEBIAN_FRONTEND noninteractive
 
@@ -32,7 +32,7 @@ RUN make website
 
 # Create a slim nginx image.
 # Final image doesn't need python or latex
-FROM nginx:1.15-alpine
+FROM nginx:1.21-alpine
 
 COPY --from=builder /data/website /data/website
 COPY --from=builder /data/nginx.conf /etc/nginx/conf.d/default.conf