x509-cert: builder requires std

Author: baloo

.github/workflows/x509-cert.yml

@@ -40,7 +40,7 @@ jobs:
           target: ${{ matrix.target }}
           override: true
       - uses: RustCrypto/actions/cargo-hack-install@master
-      - run: cargo hack build --target ${{ matrix.target }} --feature-powerset --exclude-features std,arbitrary
+      - run: cargo hack build --target ${{ matrix.target }} --feature-powerset --exclude-features std,arbitrary,builder
 
 # FIXME: Temporary disabled until https://github.com/rust-fuzz/arbitrary/issues/134 is fixed
 #  minimal-versions: