CI: Move testing of unstable features into a separate job

Closes zcash/librustzcash#1109.

.github/workflows/ci.yml

@@ -4,18 +4,50 @@ on: [push, pull_request]
 
 jobs:
   test:
-    name: Test on ${{ matrix.os }}
+    name: >
+      Test on ${{ matrix.os }}${{
+      matrix.extra_flags != 'NOT_A_PUZZLE' && format(' with --features {0}', matrix.extra_flags) || ''
+      }}
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macOS-latest]
+        extra_flags:
+          - NOT_A_PUZZLE
+          - orchard
+          - unstable-nu6
+          - zfuture
 
     steps:
       - uses: actions/checkout@v4
+      - name: Prepare feature flags
+        id: prepare
+        shell: bash
+        run: >
+          echo "flags=--features '
+          bundled-prover
+          download-params
+          lightwalletd-tonic
+          temporary-zcashd
+          transparent-inputs
+          unstable
+          unstable-serialization
+          unstable-spanning-tree
+          ${{ matrix.extra_flags != 'NOT_A_PUZZLE' && matrix.extra_flags || '' }}
+          '" >> $GITHUB_OUTPUT
       - name: Run tests
-        run: cargo test  --all-features --verbose --release --all
+        run: >
+          cargo test
+          --release
+          --workspace
+          ${{ steps.prepare.outputs.flags }}
       - name: Run slow tests
-        run: cargo test --all-features --verbose --release --all -- --ignored
+        run: >
+          cargo test
+          --release
+          --workspace
+          ${{ steps.prepare.outputs.flags }}
+          -- --ignored
       - name: Verify working directory is clean
         run: git diff --exit-code