Fix shellcheck issues

Author: vmcj

docker-gitlabci/build.sh

@@ -25,7 +25,7 @@ wget https://github.com/DOMjudge/domjudge/archive/refs/heads/main.zip
 unzip main.zip
 cd domjudge-main
   make configure
-  ./configure --with-domjudge-user=domjudge --with-judgehost_chrootdir=`pwd`/chroot
+  ./configure --with-domjudge-user=domjudge --with-judgehost_chrootdir="$(pwd)/chroot"
 cd misc-tools
   make dj_make_chroot
   sudo ./dj_make_chroot