adding explicitely imagesize python module to ensure proper image sizing

Dockerfile

@@ -10,8 +10,9 @@
 FROM sphinxdoc/sphinx-latexpdf:7.1.2
 
 RUN python -m pip install pip -U && \
-      pip install --upgrade myst-parser && \
-      pip install sphinx-rtd-theme sphinxcontrib-fulltoc linkify-it-py sphinxnotes-strike
+      pip install imagesize && \
+      pip install sphinxcontrib-fulltoc linkify-it-py sphinxnotes-strike sphinx-mermaid && \
+      pip install sphinx-rtd-theme sphinx-rtd-size
 
 RUN apt-get update && apt-get install --yes texlive-latex-recommended && apt-get autoremove  && apt-get clean  && rm -rf /var/lib/apt/lists/* # buildkit