ci: Remove "DNF CI" workflow

We would like to switch to exclusively using Packit for building and
testing pull requests, so we are retiring this GitHub Actions workflow.

In order to fully disable the action, this commit must be applied on
each branch in the upstream repository. Otherwise, the action might be
triggered by a pull request to some stale branch.

.github/workflows/ci.yml

@@ -1,73 +0,0 @@
----
-name: DNF CI
-on: pull_request_target
-
-jobs:
-  copr-build:
-    name: Copr Build
-    runs-on: ubuntu-latest
-    container:
-      image: ghcr.io/rpm-software-management/dnf-ci-host
-    outputs:
-      package-urls: ${{steps.copr-build.outputs.package-urls}}
-    steps:
-      - name: Check out ci-dnf-stack
-        uses: actions/checkout@v2
-        with:
-          repository: rpm-software-management/ci-dnf-stack
-
-      - name: Setup CI
-        id: setup-ci
-        uses: ./.github/actions/setup-ci
-        with:
-          copr-user: ${{secrets.COPR_USER}}
-          copr-api-token: ${{secrets.COPR_API_TOKEN}}
-
-      - name: Check out sources
-        uses: actions/checkout@v2
-        with:
-          path: gits/${{github.event.pull_request.head.repo.name}}
-          ref: ${{github.event.pull_request.head.sha}}  # check out the PR HEAD
-          fetch-depth: 0
-
-      - name: Run Copr Build
-        id: copr-build
-        uses: ./.github/actions/copr-build
-        with:
-          copr-user: ${{steps.setup-ci.outputs.copr-user}}
-
-  integration-tests:
-    name: DNF Integration Tests
-    needs: copr-build
-    runs-on: ubuntu-latest
-    container:
-      image: ghcr.io/rpm-software-management/dnf-ci-host
-      options: --privileged
-    steps:
-      - name: Check out ci-dnf-stack
-        uses: actions/checkout@v2
-        with:
-          repository: rpm-software-management/ci-dnf-stack
-
-      - name: Run Integration Tests
-        uses: ./.github/actions/integration-tests
-        with:
-          package-urls: ${{needs.copr-build.outputs.package-urls}}
-
-  ansible-tests:
-    name: Ansible Tests
-    needs: copr-build
-    runs-on: ubuntu-latest
-    container:
-      image: ghcr.io/rpm-software-management/dnf-ci-host
-      options: --privileged
-    steps:
-      - name: Check out ci-dnf-stack
-        uses: actions/checkout@v2
-        with:
-          repository: rpm-software-management/ci-dnf-stack
-
-      - name: Run Ansible Tests
-        uses: ./.github/actions/ansible-tests
-        with:
-          package-urls: ${{needs.copr-build.outputs.package-urls}}