fix building docker container

Author: Vauff

Dockerfile

@@ -6,7 +6,9 @@ RUN apt update && apt install -y clang-16
 RUN ln -sf /usr/bin/clang-16 /usr/bin/clang && ln -sf /usr/bin/clang++-16 /usr/bin/clang++
 RUN git clone https://github.com/alliedmodders/ambuild
 RUN cd ambuild && python setup.py install && cd ..
-RUN git clone --recurse-submodules -b k/sourcehook_alternative https://github.com/alliedmodders/metamod-source
+RUN git clone -b k/sourcehook_alternative https://github.com/alliedmodders/metamod-source
+# no recursive submodules, steamrt3 doesn't support ssh checkout
+RUN cd metamod-source && git submodule update --init && cd ..
 RUN git config --global --add safe.directory /app
 
 COPY ./docker-entrypoint.sh ./