CI: install cmake for aws-lc-sys (rustls crypto backend)

rustls 0.23 pulls aws-lc-sys, which compiles AWS-LC via cmake; the node
image has gcc/make but not cmake, so add it (plus clang) before the
build.

.forgejo/workflows/ci.yml

@@ -21,6 +21,9 @@ jobs:
       - name: Build, lint, and test
         run: |
           set -e
+          # cmake + a C compiler for aws-lc-sys (rustls's crypto backend). The
+          # node image already ships gcc/g++/make; protoc is vendored in build.rs.
+          apt-get update && apt-get install -y --no-install-recommends cmake clang
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal -c clippy
           . "$HOME/.cargo/env"
           cargo build --workspace --locked