Run linux/arm64 test on native platform

Note that, contrary to the removed TODO, emulation is still required for
some tools in the Docker image. This means usage of the runner wasn't
blocked by the latest Nextstrain CLI release, but at least the native
install means CLI itself should run more efficiently.

Author: victorlin

.github/workflows/ci.yml

@@ -145,10 +145,7 @@ jobs:
           - platform: linux/amd64
             runner: ubuntu-latest
           - platform: linux/arm64
-            # TODO: use ubuntu-24.04-arm and remove emulation when Nextstrain
-            # CLI can be installed natively on aarch64.¹
-            # ¹ <https://github.com/nextstrain/cli/pull/490>
-            runner: ubuntu-latest
+            runner: ubuntu-24.04-arm
     permissions:
       contents: read
       id-token: write