remove dnssec-tests' GHA workflow

it has been deprecated by the new `/.github/workflows/conformance.yml`
workflow

conformance/.github/workflows/ci.yml

@@ -1,52 +0,0 @@
-name: CI
-
-on:
-  pull_request:
-    branches: [main]
-  merge_group:
-
-env:
-  HICKORY_REV: 107635c6c5934524894736f1b141198d0fa62fec
-  DNS_TEST_VERBOSE_DOCKER_BUILD: 1
-
-jobs:
-  ci:
-    name: Continuous Integration
-    runs-on: ubuntu-latest
-
-    steps:
-      - name: Checkout sources
-        uses: actions/checkout@v4
-
-      - name: Install ${{ matrix.rust }} toolchain
-        uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: stable
-          components: clippy, rustfmt
-
-      - name: Run dns-test tests
-        run: cargo test -p dns-test -- --include-ignored
-
-      - name: Run tests against unbound
-        run: DNS_TEST_PEER=bind cargo test -p conformance-tests -- --include-ignored
-
-      - name: Run tests against BIND
-        run: DNS_TEST_SUBJECT=bind cargo test -p conformance-tests -- --include-ignored
-
-      - name: Run tests against hickory
-        run: |
-          git clone https://github.com/hickory-dns/hickory-dns /tmp/hickory
-          ( cd /tmp/hickory && git reset --hard ${{ env.HICKORY_REV }} )
-          DNS_TEST_SUBJECT="hickory /tmp/hickory" cargo test -p conformance-tests
-
-      - name: Check that ignored tests fail with hickory
-        run: |
-          tmpfile="$(mktemp)"
-          DNS_TEST_SUBJECT="hickory /tmp/hickory" cargo test -p conformance-tests -- --ignored | tee "$tmpfile"
-          grep 'test result: FAILED. 0 passed' "$tmpfile" || ( echo "expected ALL tests to fail but at least one passed; the passing tests must be un-#[ignore]-d" && exit 1 )
-
-      - name: Check that code is formatted
-        run: cargo fmt --all -- --check
-
-      - name: Lint code
-        run: cargo clippy --workspace --all-targets -- -D warnings