removes broken/unused changeset workflow

.github/workflows/changesets.yml

----
-name: Changeset integrity checker
-on:
-  - pull_request_target
-
-jobs:
-  changesets-integrity-checker:
-    runs-on: ubuntu-latest
-    on:
-      push:
-        branches-ignore:
-          - 'develop'
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-
-      - name: Install Dependencies
-        run: yarn
-
-      - name: Changeset Status
-        run: npx changeset status