Remove dunder methods from API docs

[nicholasjng]

Since LakeFSFile.__del__ was overloaded, it appeared in the docs, as mkdocstrings only removes single-underscore methods from the rendered documentation.

__init__ methods are excluded with a different flag already, so to fix, just extend the filter regex to double-leading-underscore methods.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (e05103d) 90.05% compared to head (d8a4154) 90.05%. Report is 3 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #222 +/- ## ======================================= Coverage 90.05% 90.05% ======================================= Files 7 7 Lines 533 533 Branches 85 85 ======================================= Hits 480 480 Misses 27 27 Partials 26 26 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.