Allow manually triggering workflows

.github/workflows/bench.yaml

@@ -4,6 +4,8 @@ on:
   create:
     tags:
       - 'v*'
+  repository_dispatch:
+    types: [wf-bench]
 
 jobs:
   bench:
@@ -13,7 +15,9 @@ jobs:
       - name: Get version
         id: version
         shell: bash
-        run: echo ::set-output name=VERSION::${GITHUB_REF#refs/tags/v}
+        run: |
+          v=${GITHUB_REF#refs/tags/v}
+          echo ::set-output name=VERSION::${v:-0.0.0}
       - name: Set up Node.js
         uses: actions/setup-node@master
         with: