set full model name for base openai models

[vipyne]

Please describe the changes in your PR. If it is addressing an issue, please reference that as well.

[codecov[bot]]

Codecov Report

:x: Patch coverage is 42.85714% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/pipecat/services/openai/base_llm.py	42.85%	4 Missing :warning:

Files with missing lines	Coverage Δ
src/pipecat/utils/tracing/service_decorators.py	6.40% <ø> (ø)
src/pipecat/services/openai/base_llm.py	34.14% <42.85%> (+0.38%)	:arrow_up:

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