Add ssh-keyscan. Start ssh-agent for cargo.

images/Dockerfile_limbo_builder

@@ -2,7 +2,9 @@
 FROM docker.io/library/fedora:latest
 
 RUN sudo dnf update -y && \
-    sudo dnf install -y nodejs yarnpkg openssl-devel curl just gcc
+    sudo dnf install -y nodejs yarnpkg \
+                        openssl-devel curl \
+                        just gcc openssh-clients
 RUN curl https://sh.rustup.rs -sSf | sh -s -- -y
 RUN /bin/bash -c "source $HOME/.cargo/env && rustup update"
 RUN /bin/bash -c "source $HOME/.cargo/env && rustup toolchain install nightly"