ci: install publicsuffix and run gated system-file PSL test

apt-get installs Debian's publicsuffix package (ships both .dat and
.dafsa). Sets LIBWEBAUTHN_PSL_SYSTEM_TEST=1 on the test step so the
SystemPublicSuffixList::auto() integration test runs against the real
system file in CI.

Author: AlfioEmanueleFresta

.github/workflows/rust.yml

@@ -14,7 +14,7 @@ jobs:
       - name: Update apt cache
         run: sudo apt-get update
       - name: Install system dependencies
-        run: sudo apt-get install libudev-dev libdbus-1-dev libsodium-dev libnfc-dev libpcsclite-dev
+        run: sudo apt-get install libudev-dev libdbus-1-dev libsodium-dev libnfc-dev libpcsclite-dev publicsuffix
       - name: Clippy
         run: cargo clippy --workspace --all-targets --all-features -- -D warnings
       - name: Check formatting
@@ -27,5 +27,7 @@ jobs:
         run: cargo build -p libwebauthn --examples --features nfc-backend-libnfc
       - name: Run tests
         run: cargo test --workspace --verbose
+        env:
+          LIBWEBAUTHN_PSL_SYSTEM_TEST: "1"
       - name: Verify libwebauthn publishes cleanly
         run: cargo publish --dry-run -p libwebauthn