standalone-installer-unix: Use new aarch64 builds for Linux

Conditions on the Nextstrain CLI version being requested, as aarch64
builds¹ will only be available going forward for new releases.  Assumes
the next release will be 10.4.2!

We must wait to merge this until after the first release (i.e. 10.4.2)
of the changes it depends on above.

¹ <#489>

Author: tsibley

.github/workflows/standalone-installers.yaml

@@ -37,6 +37,8 @@ jobs:
         os:
           - ubuntu-22.04
           - ubuntu-24.04
+          - ubuntu-22.04-arm
+          - ubuntu-24.04-arm
           - macos-13
           - macos-14      # (aarch64)
           - macos-15      # (aarch64)

bin/standalone-installer-unix

@@ -109,7 +109,9 @@ target-triple() {
 
     case "$KERNEL" in
         Linux)
-            [[ "$machine" == x86_64 ]] || die "unsupported architecture: $machine"
+               [[ "$machine" == x86_64 ]] \
+            || ([[ "$machine" == aarch64 ]] && version-gte 10.4.2) \
+            || die "unsupported architecture: $machine"
             vendor=unknown
             os=linux-gnu
             ;;