fix: test with undef input

Author: lovisaberggren

.github/workflows/ipa-release.yml

@@ -49,7 +49,7 @@ jobs:
     needs: check-version
     if: >-
       !cancelled()
-      && inputs.use_existing_tag == 'false'
+      && (!inputs.use_existing_tag || inputs.use_existing_tag == 'false')
     steps:
       - name: Validation of version format
         run: |