chore(ci): remove unused action

.forgejo/workflows/tests.yml

@@ -1,15 +0,0 @@
-name: Tests
-on: push
-jobs:
-  test:
-    runs-on: alpine-node
-    steps:
-      - name: Checkout
-        run: git clone --depth 1 \
-            http://${{ github.repository_owner }}:${{ secrets.GITHUB_TOKEN }}@${{ secrets.FORGEJO_DOMAIN }}/dot013/.vault
-      - name: Install nix
-        uses: actions/nix-quick-install-action@v27
-      - name: Setup cachix
-        uses: actions/cachix-action@master
-      - name: Test crate
-        run: cargo test