Dockerfile: Use same command to update and install

Use `apt update` in the same `RUN` command with `app install`. This
prevents package synchronzation issues during installation.

Signed-off-by: Razvan Deaconescu <razvan.deaconescu@upb.ro>

Dockerfile

 FROM gitlab.cs.pub.ro:5050/operating-systems/assignments-docker-base
 
-RUN apt install -yqq nasm
-RUN apt install -yqq strace
-RUN apt install -yqq ltrace
-RUN apt install -yqq binutils
+RUN apt update && \
+	apt install -yqq nasm strace ltrace binutils
 
 COPY ./checker ${CHECKER_DATA_DIRECTORY}
 RUN mkdir ${CHECKER_DATA_DIRECTORY}/../tests