refactor(standard-tests): improve VCR config

[cbornet]

Use of the fixture _base_vcr_config is deprecated with alternative function base_vcr_config()
This way:

• we don't need to import _base_vcr_config seen as unused (which leads to PLC0414 and F811)
• we don't need to make a copy since a new dict is created at each function invocation

[codspeed-hq]

CodSpeed Performance Report

Merging #33968 will not alter performance

_{Comparing cbornet:base_vcr_config (4a54f3e) with master (275dcbf)}

Summary

✅ 10 untouched
⏩ 24 skipped¹

Footnotes

1. 24 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩