CI: reduce test matrix

For the sake or reducing test flakes

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

Author: AkihiroSuda

.github/workflows/lima.yaml

@@ -16,13 +16,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        # macos-13-large is used as macos-13 seems too flaky.
-        # macos-14 (ARM) and later cannot be used for the most part of the job
-        # due to the lack of the support for nested virt.
         platform:
-          - macos-13-large
-          - macos-14-large
-          - macos-15-large
+          - macos-15-large  # Intel
     runs-on: ${{ matrix.platform }}
     # Typically takes 8 minutes. If a step get stuck for many mintues it is
     # unlikely to succeed.