build(python): Add linux-musl-riscv64 for python binaries

Build polars Python modules for riscv64 platforms with musl by using the
riscv64gc-unknown-linux-musl target. Use a RISE riscv native runner as
the 'os'.

See: https://riseproject-dev.github.io/riscv-runner/

Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>

Author: threexc

.github/workflows/release-python.yml

@@ -153,7 +153,7 @@ jobs:
       fail-fast: false
       matrix:
         package: [polars-runtime-32, polars-runtime-64, polars-runtime-compat]
-        job_config: [linux-x64, linux-arm64, linux-riscv64, linux-musl-x64, linux-musl-arm64, macos-x64, macos-arm64, win-x64, win-arm64]
+        job_config: [linux-x64, linux-arm64, linux-riscv64, linux-musl-x64, linux-musl-arm64, linux-musl-riscv64, macos-x64, macos-arm64, win-x64, win-arm64]
         include:
           - job_config: linux-x64
             os: ubuntu-latest
@@ -175,6 +175,10 @@ jobs:
             os: linux-arm-large
             architecture: aarch64
             target: aarch64-unknown-linux-musl
+          - job_config: linux-musl-riscv64
+            os: ubuntu-24.04-riscv
+            architecture: riscv64
+            target: riscv64-unknown-linux-musl
           - job_config: macos-x64
             os: macos-15-intel
             architecture: x86-64