fix: call `KNNMixin._dtw1d` when `independent=True`

[eonu]

Description

Fixes #250 (was calling wrong DTW function).

Checklist

• [x] I have added new tests (if necessary).
• [x] I have ensured that tests and coverage are passing on CI.
• [x] I have updated any relevant documentation (if necessary).
• [x] I have used a descriptive pull request title.

[coveralls]

Pull Request Test Coverage Report for Build 587dc8de-10f4-4295-832b-1504ba8e266d

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 90.868%

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Totals
Change from base Build d31d7ff8-d7b5-47c4-bbc7-8b83b833affb:	0.2%
Covered Lines:	2199
Relevant Lines:	2420

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💛 - Coveralls