Remove an unused workflow

.github/workflows/_post-comment.yml

@@ -1,23 +0,0 @@
-name: Post comment
-
-on:
-  workflow_call:
-    inputs:
-      url:
-        type: string
-        required: true
-      message:
-        type: string
-        required: true
-
-jobs:
-  notify:
-    runs-on: ubuntu-latest
-    steps:
-      - run: |
-          export GITHUB_TOKEN="$GH_TOKEN_SECRET"
-          gh issue comment "$ISSUE_URL" --body "$MESSAGE"
-        env:
-          ISSUE_URL: ${{ inputs.url }}
-          MESSAGE: ${{ inputs.message }}
-          GH_TOKEN_SECRET: ${{ github.token }}