refactor: Made _T_DIST_95_CONF_LEVELS a tuple because it's a constant…

[DebanKsahu]

Description

• I was reading the code and saw that _T_DIST_95_CONF_LEVELS never modified in the later part of _utils.py file as it is only accessed so I thought it is reasonable to make it a tuple instead of the dynamic list.
• This has no significant performance gain, but I think it would avoid the amortized space allocation for dynamic list in python which happens to avoid amortized O(N) complexity for append operation

[vstinner]

This is really a pedantic change... It's a private constant in a private module, the constant is only used by tdist95conf_level().

This has no significant performance gain, but I think it would avoid the amortized space allocation for dynamic list in python which happens to avoid amortized O(N) complexity for append operation

_T_DIST_95_CONF_LEVELS is never modified, so this point is irrelevant.

I only approved the change to avoid someone else proposing a similar change in the future.

[DebanKsahu]

Sorry, I will be careful with the future code changes if I made any.