ci: add riscv64 wheel builds

RISC-V wheels have been supported by cibuildwheel and PyPI for a while,
so let's build binary wheels for it as many of the boards currently on
the market are rather slow to make building on the spot rather painful.

Human note: The entirety of the commit message is written manually.

See: pypa/cibuildwheel#2366
See: pypi/warehouse#18243
Assisted-by: GPT-5.5

Author: xen0n

.github/workflows/wheels.yml

@@ -108,6 +108,9 @@ jobs:
         - name: linux-ppc64le
           qemu_platform: linux/ppc64le
           cibw_arch: ppc64le
+        - name: linux-riscv64
+          qemu_platform: linux/riscv64
+          cibw_arch: riscv64
 
     steps:
       - uses: actions/setup-python@v6

pyproject.toml

@@ -15,10 +15,10 @@ before-all = "sh build.sh"
 test-command = "pytest"
 test-sources = ["test", "pytest.ini"]
 before-test = "pip install -r {package}/requirements-test.txt"
-# Will avoid testing on emulated architectures (specifically ppc64le)
+# Will avoid testing on emulated architectures (specifically ppc64le and riscv64)
 # Also, skip testing pypy on macOS arm64 due issue with bootstrapping git config paths
 # see https://github.com/libgit2/pygit2/issues/1442
-test-skip = "*-*linux_ppc64le pp*-macosx_arm64"
+test-skip = "*-*linux_ppc64le *-*linux_riscv64 pp*-macosx_arm64"
 
 [tool.cibuildwheel.linux]
 repair-wheel-command = "LD_LIBRARY_PATH=/project/ci/lib64 auditwheel repair -w {dest_dir} {wheel}"