CI: Only untar artifacts that are tarred

Docs aren't tarred, because they don't need to be.
It still makes sense to upload them with the release,
though, so this is the better way to patch the issue.

Author: YuriSizov

.github/workflows/publish-project.yml

@@ -33,8 +33,10 @@ jobs:
           for name in ./*; do
             if [ -d "$name" ]; then
               cd "./$name"
-              tar -xvf boscaceoil-blue.tar
-              rm -f boscaceoil-blue.tar
+              if [ -f "boscaceoil-blue.tar" ]; then
+                tar -xvf boscaceoil-blue.tar
+                rm -f boscaceoil-blue.tar
+              fi
               cd ..
             fi
           done