Use Ubuntu instead of Debian in docker file

See djsudduth/keep-it-markdown#72 (comment) for reasons why.

Dockerfile

@@ -1,11 +1,11 @@
-FROM debian:bullseye
+FROM ubuntu:22.04
 RUN apt update
 RUN apt install -y python-is-python3 python3-pip
 RUN apt-get install -y curl
 RUN apt-get install ca-certificates
-RUN curl -L -o tmp/keep-it-markdown-0.5.2.tar.gz https://github.com/djsudduth/keep-it-markdown/archive/refs/tags/0.5.2.tar.gz
-RUN tar -zxvf tmp/keep-it-markdown-0.5.2.tar.gz
-RUN pip install -r keep-it-markdown-0.5.2/requirements.txt
+RUN curl -L -o tmp/keep-it-markdown-0.5.4.tar.gz refs/tags/0.5.4.tar.gz
+RUN tar -zxvf tmp/keep-it-markdown-0.5.4.tar.gz
+RUN pip install -r keep-it-markdown-0.5.4/requirements.txt
 RUN pip install requests==2.23.0
 RUN pip install gpsoauth==1.0.2
-RUN pip install keyrings.alt
+RUN pip install keyrings.alt