release process: don't create "uploaded" marker file in release.sh

No longer needed with the "chmod 444 *" trick in 697c700a1f.
(it is now cheap to re-run upload.sh, it no longer redundantly re-uploads hundreds of MBs)

contrib/release.sh

@@ -258,12 +258,7 @@ else
     fi
 
     # upload the files
-    if test -f dist/uploaded; then
-        info "files already uploaded"
-    else
-        ./contrib/upload.sh
-        touch dist/uploaded
-    fi
+    ./contrib/upload.sh
 
 fi