Improve question generation efficiency In Response Relevancy metrics

[hundredeuk2]

Description: This update refactors the _ascore method to use asyncio.gather for parallel execution of question generation tasks. Key improvements include:

Issue : When ResponseRelevancy evaluation loops based on the strictness variable (default 3), which is taking longer than expected

Performance Enhancement: By processing all tasks concurrently, the overall execution time is significantly reduced, especially for high strictness values.
Code Simplification: The refactored code is more concise and aligns better with Python's asynchronous programming patterns.
Scalability: The new implementation handles a larger number of tasks without blocking, making it more suitable for use cases requiring high concurrency.
Backward Compatibility: All existing functionality remains intact, with no changes required to external interfaces.

This change improves the efficiency and maintainability of the codebase, aligning with best practices for asynchronous programming in Python.

Result after resolution : Average 1 run of Example code based on tutorial code (10 runs total) reduced to 4.35s => 2.82s

[hundredeuk2]

Speed difference when experimenting with the entire dataset during the tutorial

which is

from datasets import load_dataset
dataset = load_dataset(
    "explodinggradients/amnesty_qa",
    "english_v3",
    trust_remote_code=True
)

before fix the code

25.063s

delta_times = [25.36874794960022,
 29.800117015838623,
 23.23536705970764,
 26.765387058258057,
 24.31095004081726,
 25.598613023757935,
 25.597922801971436,
 24.84323501586914,
 22.47859835624695,
 22.639552116394043]

after fix the code

23.32s

delta_times = [21.71244788169861,
 20.64484715461731,
 21.470897912979126,
 29.34908390045166,
 20.96466302871704,
 23.604390144348145,
 19.539119720458984,
 21.615919828414917,
 26.599979162216187,
 27.745948314666748]

[jjmachan]

hey @hundredeuk2 thank you so much for improving the codebase we really appreciate that - merging this now