Series.hist with bin_count produces wrong result if all values are the same

[coastalwhite]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

pl.Series([1, 1]).hist(bin_count=2)

shape: (2, 3)
┌────────────┬────────────┬───────┐
│ breakpoint ┆ category   ┆ count │
│ ---        ┆ ---        ┆ ---   │
│ f64        ┆ cat        ┆ u32   │
╞════════════╪════════════╪═══════╡
│ 1.0        ┆ (1.0, 1.0] ┆ 2     │
│ 1.0        ┆ (1.0, 1.0] ┆ 0     │
└────────────┴────────────┴───────┘

Log output

No response

Issue description

The output is incorrect.

This also causes a flaky failure of tests/unit/operations/test_hist.py::test_hist_rand.

Expected behavior

Correct output.

Installed versions

Replace this line with the output of pl.show_versions(). Leave the backticks in place.

[mcrumiller]

Thanks @coastalwhite, I updated hist recently so this is my fault. This is a quick fix.