feat: upgrade azure speech sdk version in azure asr

[sunxilin]

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[github-actions]

PR Review: upgrade azure speech sdk version in azure asr

Overall: This is a straightforward dependency upgrade. The change is small and well-scoped. A few minor observations:

1. Version jump spans 3 minor releases (1.45.0 to 1.48.2)
   Upgrading across three minor versions can occasionally bring behavioral changes in speech recognition, audio handling, or event callbacks. It would be helpful to note in the PR description what prompted the upgrade (bug fix, new feature, security patch, etc.).

2. PR commit type label
   The title uses feat: prefix, but a dependency version bump is more conventionally labeled chore: or build:. Not blocking, just a consistency note.

3. Missing newline at end of requirements.txt
   The diff shows the missing trailing newline is preserved in the updated file. Since requirements.txt is being touched in this PR, it would be clean to add a newline after the last line (aiofiles).

4. No test evidence
   The PR does not reference any test results confirming the upgraded SDK behaves correctly. Given the jump spans multiple minor versions, a note confirming the ASR guarder tests pass would add confidence (task asr-guarder-test EXTENSION=azure_asr_python CONFIG_DIR=tests/configs).

Summary: The manifest version bump (0.2.7 to 0.2.8) is appropriate. No code logic changes are introduced, limiting the risk. Please confirm the SDK upgrade has been tested and note in the PR description why the upgrade was needed.