Run Bazel test suite on Linux ARM64 platform

Update .bazelversion and support matrix after releasing Bazel 8.1.0

Failed in 4m 12s
:ubuntu: Ubuntu 20.04 LTS ARM64curl -sS https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/bazelci.py?1739523918 -o bazelci.py && python3.8 bazelci.py runner --task=ubuntu2004_arm64 --http_config=https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/pipelines/bazel-linux-arm64.yml?1739523917
Waited 6s
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Ran in 3m 30s
Total Job Run Time: 4m 7s