Run tar only tags (#25)

Author: AsaiYusuke

.github/workflows/make.yml

@@ -31,6 +31,7 @@ jobs:
         base-path: "./example"
 
     - name: Make tarball
+      if: startsWith(github.ref, 'refs/tags/')
       run: tar cvjf linux.tar.bz2 6502_tester LICENSE README.md
 
     - name: Release