x509-cert: provide zlint in CI

Author: baloo

.github/workflows/x509-cert.yml

@@ -64,6 +64,12 @@ jobs:
           toolchain: ${{ matrix.rust }}
           override: true
       - uses: RustCrypto/actions/cargo-hack-install@master
+      - name: Install zlint
+        run: |
+          wget -O /tmp/zlint.tar.gz https://github.com/zmap/zlint/releases/download/v3.4.1/zlint_3.4.1_Linux_x86_64.tar.gz
+          tar -C /tmp/ -zxf /tmp/zlint.tar.gz --strip-components 1
+          mv /tmp/zlint ${RUNNER_TOOL_CACHE}
+          echo "${RUNNER_TOOL_CACHE}" >> $GITHUB_PATH
       - run: cargo hack test --feature-powerset
 
   fuzz: