fix coverage typing and lint checks
This gets make working without errors and puts the code coverage back up to 100% (at least on my mac - we should make sure that in fact the CI pipeline is also at 100%)
---------- coverage: platform darwin, python 3.9.21-final-0 ----------
Name Stmts Miss Cover Missing
-----------------------------------------------------------------
src/sgnts/base/array_backend.py 31 0 100%
src/sgnts/base/array_ops.py 20 0 100%
src/sgnts/base/audioadapter.py 139 0 100%
src/sgnts/base/buffer.py 292 0 100%
src/sgnts/base/notorch_backend.py 5 0 100%
src/sgnts/base/numpy_backend.py 42 0 100%
src/sgnts/base/offset.py 35 0 100%
src/sgnts/base/slice_tools.py 117 0 100%
src/sgnts/base/time.py 6 0 100%
src/sgnts/base/torch_backend.py 47 0 100%
src/sgnts/sources/fake_series.py 79 0 100%
src/sgnts/sources/segment.py 24 0 100%
src/sgnts/transforms/adder.py 38 0 100%
src/sgnts/transforms/align.py 15 0 100%
src/sgnts/transforms/amplify.py 22 0 100%
src/sgnts/transforms/converter.py 52 0 100%
src/sgnts/transforms/correlate.py 43 0 100%
src/sgnts/transforms/gate.py 19 0 100%
src/sgnts/transforms/matmul.py 27 0 100%
src/sgnts/transforms/resampler.py 101 0 100%
src/sgnts/transforms/sumindex.py 34 0 100%
src/sgnts/transforms/threshold.py 40 0 100%
src/sgnts/utils.py 20 0 100%
-----------------------------------------------------------------
TOTAL 1248 0 100%