ci: build armv7l wheels on native ARM runners

GitHub provides public hosted Linux ARM64 runners (`ubuntu-24.04-arm`),
so the armv7l wheel build no longer needs an x86_64 host under it. QEMU
stays registered so binfmt picks up the 32-bit ARM userspace handler
whether or not the host kernel has CONFIG_COMPAT enabled, and even with
emulation, armv7l-on-aarch64 is far cheaper than the previous
armv7l-on-x86_64 path.

The aarch64 wheels were already native via `ubuntu-24.04-arm` in the
base matrix, and ppc64le, s390x, and riscv64 keep their `ubuntu-latest`
+ QEMU setup since there are no native GH-hosted runners for those.

Author: bdraco

.github/workflows/ci-cd.yml

@@ -546,10 +546,15 @@ jobs:
         - os: ubuntu-latest
           qemu: s390x
           musl: musllinux
-        - os: ubuntu-latest
+        # armv7l builds on aarch64 hosts. We still register QEMU so
+        # binfmt picks up the 32-bit ARM userspace handler regardless of
+        # whether the host kernel has CONFIG_COMPAT enabled. Even with
+        # emulation, aarch64-on-aarch64 hosting beats x86_64 by a wide
+        # margin.
+        - os: ubuntu-24.04-arm
           qemu: armv7l
           musl: ""
-        - os: ubuntu-latest
+        - os: ubuntu-24.04-arm
           qemu: armv7l
           musl: musllinux
         - os: ubuntu-latest

CHANGES/12652.contrib.rst

@@ -0,0 +1,4 @@
+Switched the armv7l wheel builds onto GitHub's hosted ARM runners. The
+32-bit ARM build still runs under QEMU, but the host is now aarch64
+rather than x86_64, so the emulation overhead drops sharply
+-- by :user:`bdraco`.

docs/spelling_wordlist.txt

@@ -1,3 +1,4 @@
+aarch
 abc
 ABI
 addons