remove upgradeable trigger workflow

(cherry picked from commit 426b33e8)

.github/workflows/upgradeable.yml

-name: Upgradeable Trigger
-
-on:
-  push:
-    branches:
-      - master
-      - release-v*
-
-jobs:
-  trigger:
-    runs-on: ubuntu-latest
-    steps:
-      - id: app
-        uses: getsentry/action-github-app-token@v1
-        with:
-          app_id: ${{ secrets.UPGRADEABLE_APP_ID }}
-          private_key: ${{ secrets.UPGRADEABLE_APP_PK }}
-      - run: |
-          curl -X POST \
-            https://api.github.com/repos/OpenZeppelin/openzeppelin-contracts-upgradeable/dispatches \
-            -H 'Accept: application/vnd.github.v3+json' \
-            -H 'Authorization: token ${{ steps.app.outputs.token }}' \
-            -d '{ "event_type": "Update", "client_payload": { "ref": "${{ github.ref }}" } }'