Drop python 3.6 support

[dvora-h]

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Description of change

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[codecov-commenter]

Codecov Report

Merging #2306 (5a34451) into master (f665bd3) will decrease coverage by 0.03%.
The diff coverage is 86.36%.

@@            Coverage Diff             @@
##           master    #2306      +/-   ##
==========================================
- Coverage   92.05%   92.01%   -0.04%     
==========================================
  Files         109      109              
  Lines       28134    28061      -73     
==========================================
- Hits        25899    25821      -78     
- Misses       2235     2240       +5     

Impacted Files	Coverage Δ
setup.py	0.00% <ø> (ø)
tests/test_asyncio/test_bloom.py	99.54% <ø> (-0.01%)	⬇️
tests/test_asyncio/test_connection.py	98.50% <ø> (-0.07%)	⬇️
tests/test_asyncio/test_monitor.py	90.74% <ø> (-0.49%)	⬇️
tests/test_asyncio/test_pipeline.py	100.00% <ø> (ø)
tests/test_asyncio/test_search.py	98.34% <ø> (-0.34%)	⬇️
tests/test_asyncio/test_timeseries.py	100.00% <ø> (ø)
redis/asyncio/cluster.py	90.28% <50.00%> (ø)
redis/asyncio/connection.py	85.66% <60.00%> (+0.20%)	⬆️
redis/asyncio/lock.py	99.09% <100.00%> (-0.04%)	⬇️
... and 15 more

---

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[utkarshgupta137]

Can you also remove asyncio.ensure_future in favour of asyncio.create_task

[dvora-h]

@utkarshgupta137 I missed your comment by 30 seconds... will do in a separate PR