chore(ci): Fix python3-clang version to 10.0.1

Ubuntu only ships clang 10 so python3-clang 11 is not working.  Fix it
to the older version.

docker/deploy-env/Dockerfile

@@ -10,7 +10,7 @@ RUN set -e -x ;\
         llvm \
         python3-pip ;\
     pip3 install \
-        clang \
+        clang==10.0.1 \
         sphinx \
         sphinx_rtd_theme ;\
     rm -rf /var/lib/apt/lists