github: fix missing version prefix

Signed-off-by: Kentaro Hayashi <hayashi@clear-code.com>

Author: kenhys

.github/workflows/add-to-project.yml

@@ -10,7 +10,7 @@ jobs:
     name: Add issue to project
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/add-to-project@1.0.2
+      - uses: actions/add-to-project@v1.0.2
         with:
           project-url: https://github.com/orgs/fluent/projects/4
           github-token: ${{ secrets.ADD_TO_PROJECT_PAT }}