[Feature] Add Zong (2003) ECG peak detection method

[anshu-97]

No description provided.

[codecov-commenter]

Codecov Report

Merging #663 (811c3da) into dev (773d748) will decrease coverage by 0.19%.
The diff coverage is 14.81%.

@@            Coverage Diff             @@
##              dev     #663      +/-   ##
==========================================
- Coverage   53.21%   53.02%   -0.20%     
==========================================
  Files         269      270       +1     
  Lines       12112    12222     +110     
==========================================
+ Hits         6446     6481      +35     
- Misses       5666     5741      +75     

Impacted Files	Coverage Δ
neurokit2/ecg/ecg_peaks.py	100.00% <ø> (ø)
neurokit2/ecg/ecg_findpeaks.py	73.18% <14.81%> (-2.74%)	⬇️
neurokit2/rsp/rsp_simulate.py	94.64% <0.00%> (-3.58%)	⬇️
neurokit2/epochs/epochs_create.py	81.48% <0.00%> (-3.14%)	⬇️
neurokit2/data/read_bitalino.py	8.90% <0.00%> (-0.36%)	⬇️
neurokit2/hrv/hrv_nonlinear.py	65.09% <0.00%> (ø)
neurokit2/events/events_find.py	80.95% <0.00%> (ø)
neurokit2/complexity/__init__.py	100.00% <0.00%> (ø)
neurokit2/signal/signal_filter.py	64.89% <0.00%> (ø)
neurokit2/complexity/fractal_dfa.py	60.78% <0.00%> (ø)
... and 8 more

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