Prune output of sha256sum to the hash alone

This causes the equality not to fail simply because the file names are
different.

.github/workflows/stack_size.yml

@@ -49,7 +49,7 @@ jobs:
           done
 
           find . -iname "monerod-*" | while read -r bin; do
-            if [ ! $(sha256sum monerod-chelf) = $(sha256sum $bin) ]; then
+            if [ ! $(sha256sum monerod-chelf | cut -d' ' -f1) = $(sha256sum $bin | cut -d' ' -f1) ]; then
               exit 1
             fi
           done