Specify correct version of add-to-project action. (#61)

Author: drewoldag

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

@@ -10,7 +10,7 @@ jobs:
     name: Add issue to project
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/add-to-project@RELEASE_VERSION
+      - uses: actions/add-to-project@v0.4.0
         with:
           # You can target a repository in a different organization
           # to the issue