Merge #20955: test: Fix get_previous_releases.py for aarch64

fa1d5e5137 test: Fix get_previous_releases.py for aarch64 (MarcoFalke)

Pull request description:

  Otherwise it will fail with "Not sure which binary to download..."

ACKs for top commit:
  laanwj:
    Code review ACK fa1d5e5137

Tree-SHA512: 0db71e898a431665757ce835016a4e05c629a95abc4a2951eac9bd9b5876ec3dc3d6f156d58565e2bcdf918cde4f2649183d4a58038ac13c705a7e914c0094d1

test/get_previous_releases.py

@@ -175,6 +175,7 @@ def check_host(args) -> int:
         './depends/config.guess').decode())
     if args.download_binary:
         platforms = {
+            'aarch64-*-linux*': 'aarch64-linux-gnu',
             'x86_64-*-linux*': 'x86_64-linux-gnu',
             'x86_64-apple-darwin*': 'osx64',
         }