Fix data type check for padding short complex pings

[ctuguinay]

When testing SWFSC RAW files, there was a file where range was adaptive and based on bottom. When open_raw is called, these pings need to be padded because they are short and non-uniform with the other short pings. In this padding code, there was a snippet that relied on complex_ to work, but complex_ is complex128, while our data is complex64. I changed this to instead use complex64.

[codecov-commenter]

Codecov Report

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

Project coverage is 78.81%. Comparing base (9f56124) to head (26ecb36). Report is 119 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1353 +/- ## ========================================== - Coverage 83.52% 78.81% -4.71% ========================================== Files 64 16 -48 Lines 5686 2700 -2986 ========================================== - Hits 4749 2128 -2621 + Misses 937 572 -365 ``` | [Flag](https://app.codecov.io/gh/OSOceanAcoustics/echopype/pull/1353/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OSOceanAcoustics) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/OSOceanAcoustics/echopype/pull/1353/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OSOceanAcoustics) | `78.81% <100.00%> (-4.71%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OSOceanAcoustics#carryforward-flags-in-the-pull-request-comment) to find out more.

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