Remove signoff action as it will not work with forked repositories

.github/workflows/signoff_mr.yml

@@ -1,47 +0,0 @@
-on: issue_comment
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/github-script@v5
-        if: github.event.action == 'created'
-        with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          script: |
-            const isValidSignOff = (
-              context.payload.action === 'created' &&
-              context.payload.issue.pull_request &&
-              context.payload.comment.user.id === context.payload.issue.user.id &&
-              context.payload.comment.body === '/signoff'
-            )
-            if (!isValidSignOff) return
-            const pr = await github.pulls.get({
-              ...context.repo,
-              pull_number: context.payload.issue.number
-            })
-            const commits = await github.pulls.listCommits({
-              ...context.repo,
-              pull_number: context.payload.issue.number
-            })
-            const baseCommit = await github.git.getCommit({
-              ...context.repo,
-              commit_sha: pr.data.head.sha
-            })
-            const tree = await github.git.getTree({
-              ...context.repo,
-              tree_sha: baseCommit.data.tree.sha
-            })
-            const commitLines = commits.data.map(item => `- ${item.sha.slice(0, 6)}: ${item.commit.message}`).join('\n')
-            const header = `I, @${context.payload.comment.user.login}, hereby signoff on these commits:`
-            const newCommit = await github.git.createCommit({
-              ...context.repo,
-              message: `${header}\n\n${commitLines}`,
-              tree: tree.data.sha,
-              parents: [pr.data.head.sha]
-            })
-            await github.git.updateRef({
-              ...context.repo,
-              ref: `heads/${pr.data.head.ref}`,
-              sha: newCommit.data.sha
-            })