Fix Google DNS bulk record docstring syntax

[nightcityblade]

Fix Google DNS bulk record docstring syntax

Description

Fixes #1936.

The GoogleDNSDriver.ex_bulk_record_changes docstring mixed a field-list
continuation with an unmarked, inconsistently indented dictionary example.
Sphinx/docutils therefore emitted three warnings while generating the API
documentation. This change aligns the continued parameter description and
marks the example as a Python code block, without changing runtime behavior.

Status

Done, ready for review.

Checklist (tick everything that applies)

• Code linting (flake8 and Black check pass)
• Documentation (Sphinx 6.2.1 dummy build passes; the three warnings for this docstring are gone)
• Tests (11 passed in libcloud/test/dns/test_google.py)
• ICLA (N/A; small documentation-only correction)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.58%. Comparing base (99aa044) to head (6f8e55d).
⚠️ Report is 11 commits behind head on trunk.

Additional details and impacted files

@@           Coverage Diff           @@
##            trunk    #2182   +/-   ##
=======================================
  Coverage   83.58%   83.58%           
=======================================
  Files         352      352           
  Lines       81808    81808           
  Branches     8769     8769           
=======================================
  Hits        68373    68373           
  Misses      10562    10562           
  Partials     2873     2873           

Files with missing lines	Coverage Δ
libcloud/dns/drivers/google.py	82.09% <ø> (ø)

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