docker: run interactively only if we have a TTY

When building packages in containers, we pass options to docker.
However, when running in a noninteractive environment such as GitHub
Actions, we can't use the -i option, since standard input will not be a
TTY and docker will consequently fail.  Check for a TTY and pass the -i
option only if one is present.

docker/run_dockers.bsh

@@ -69,7 +69,11 @@ for IMAGE_NAME in "${IMAGES[@]}"; do
   fi
 
   #It CAN'T be empty () with set -u... So I put some defaults in here
-  OTHER_OPTIONS=("-it")
+  OTHER_OPTIONS=("-t")
+
+  if tty >/dev/null; then
+    OTHER_OPTIONS+=("-i")
+  fi
 
   if [ "${AUTO_REMOVE-1}" == "1" ]; then
     OTHER_OPTIONS+=("--rm")