fix(workflows): correct ARM64 Linux runner labels

Changes ubuntu-24.04-arm64 → ubuntu-24.04-arm for Linux ARM64 builds.

The correct GitHub Actions runner label is ubuntu-24.04-arm, not
ubuntu-24.04-arm64. This was causing alpine-arm64 and linux-arm64
jobs to remain permanently queued with no available runners.

GitHub's ARM64 Linux runners became generally available in public
repositories in 2025 with the labels:
- ubuntu-22.04-arm
- ubuntu-24.04-arm

These runners are free for public repositories.

Affected workflows:
- build-smol.yml (linux-arm64, alpine-arm64)
- build-sea.yml (linux-arm64, alpine-arm64)

References:
- https://github.blog/changelog/2025-01-16-linux-arm64-hosted-runners-now-available-for-free-in-public-repositories-public-preview/
- https://github.blog/changelog/2025-08-07-arm64-hosted-runners-for-public-repositories-are-now-generally-available/

Author: jdalton

.github/workflows/build-sea.yml

@@ -129,7 +129,7 @@ jobs:
             os: linux
             platform: linux
             arch: x64
-          - runner: ubuntu-24.04-arm64
+          - runner: ubuntu-24.04-arm
             os: linux
             platform: linux
             arch: arm64
@@ -139,7 +139,7 @@ jobs:
             os: linux
             platform: alpine
             arch: x64
-          - runner: ubuntu-24.04-arm64
+          - runner: ubuntu-24.04-arm
             os: linux
             platform: alpine
             arch: arm64

.github/workflows/build-smol.yml

@@ -129,7 +129,7 @@ jobs:
             os: linux
             platform: linux
             arch: x64
-          - runner: ubuntu-24.04-arm64
+          - runner: ubuntu-24.04-arm
             os: linux
             platform: linux
             arch: arm64
@@ -139,7 +139,7 @@ jobs:
             os: linux
             platform: alpine
             arch: x64
-          - runner: ubuntu-24.04-arm64
+          - runner: ubuntu-24.04-arm
             os: linux
             platform: alpine
             arch: arm64