[NRL-1179] Switch ADD to COPY in Dockerfile

Author: mattdean3-nhs

Dockerfile.ci-build

@@ -20,7 +20,7 @@ RUN git clone https://github.com/asdf-vm/asdf.git ~/.asdf --branch v0.13.1 && \
     echo "export PATH=\$ASDF_DIR/bin:\$PATH" >> ~/.bashrc && \
     echo "export PATH=\$ASDF_DIR/shims:\$PATH" >> ~/.bashrc
 
-ADD .tool-versions .
+COPY .tool-versions .
 RUN for plugin in $(cat .tool-versions | cut -d' ' -f1); do \
         ./.asdf/bin/asdf plugin add $plugin; \
     done && \