CI: Add RISC-V runners to base CI (via RISE project)

The RISE project now provides free RISC-V Github runners, see
https://riseproject-dev.github.io/riscv-runner/
This commit adds them to the Quickcheck and Quickcheck ACVP jobs
of the base CI.

The C90 and scan-build jobs are intentionally not enabled on
RISC-V as they are slow.
We can't run the extended CI on RISC-V as those require nix
which does not yet support RISC-V.

Signed-off-by: Matthias J. Kannwischer <matthias@zerorisc.com>

Author: mkannwischer

.github/workflows/base.yml

@@ -34,6 +34,9 @@ jobs:
            name: 'aarch64'
          - runner: ubuntu-latest
            name: 'x86_64'
+         # via https://riseproject-dev.github.io/riscv-runner/
+         - runner: ubuntu-24.04-riscv
+           name: 'riscv'
          - runner: macos-latest
            name: 'macos (aarch64)'
          - runner: macos-15-intel
@@ -68,6 +71,9 @@ jobs:
            name: 'aarch64'
          - runner: ubuntu-latest
            name: 'x86_64'
+         # via https://riseproject-dev.github.io/riscv-runner/
+         - runner: ubuntu-24.04-riscv
+           name: 'riscv'
         acvp-version: [v1.1.0.39, v1.1.0.40, v1.1.0.41]
         exclude:
           - {external: true,