Bump version to 1.6.4

[Bre77]

Intent

• Ship release 1.6.4: PR feat: add command debug logging #64 (command debug logging) merged to main but was never released on top of published 1.6.3.
  • Captain-authorized release cut, no functional changes in this PR.

What Changed

• Bump version in pyproject.toml: 1.6.3 -> 1.6.4
• Bump __version__ in tesla_fleet_api/__init__.py: 1.6.3 -> 1.6.4
• Verified no other 1.6.3 version pins exist elsewhere in the repo (grep clean).

Risk Assessment

• None: version-only bump, no code changes.

Testing

• N/A - no functional changes.

Release Flow

• On merge, a maintainer tags the merge commit v1.6.4 and pushes the tag, which triggers .github/workflows/python-publish.yml to build and publish to PyPI.

Full narrative / original brief

Cut python-tesla-fleet-api release 1.6.4. Captain-authorized: main's merged command debug-logging (PR #64) is unreleased on top of published 1.6.3.

Do, in order:

1. Branch off origin/main. Bump the version to 1.6.4 in BOTH pyproject.toml and tesla_fleet_api/init.py (verify no other version pins exist - grep for 1.6.3).
2. Open the bump PR and append done: PR {url} - awaiting merge, then I tag. STOP and wait.
3. Firstmate will merge and steer you to continue. THEN: fetch origin, verify the bump commit is in origin/main, tag that main commit v1.6.4 and push the tag to origin (the tag push is authorized - it is how python-publish.yml ships to PyPI; you are still never pushing the main branch itself).
4. Watch the publish workflow (gh run list/watch) until it completes, then verify https://pypi.org/pypi/tesla-fleet-api/json reports 1.6.4.
5. Append done: 1.6.4 on PyPI and stop. If the workflow fails, append failed: with the run URL and stop.