Update free-disk-space.sh

Author: ChrisDenton

src/ci/scripts/free-disk-space.sh

@@ -11,7 +11,7 @@ if [[ "$1" == "start" ]]; then
     else
         $script_dir/free-disk-space-linux.sh &> $log &
     fi
-    FREE_DISK_SPACE_PID=$! >> $GITHUB_ENV
+    echo "FREE_DISK_SPACE_PID=$!" >> $GITHUB_ENV
 elif [[ "$1" == "report" ]]; then
     wait $FREE_DISK_SPACE_PID
     exit_code=$?