Support work_group parameter in query execution (fix #69)

[laughingman7743]

https://docs.aws.amazon.com/ja_jp/athena/latest/ug/workgroups-create-update-delete.html#specify-wkgroup-to-athena-in-which-to-run-queries
https://docs.aws.amazon.com/ja_jp/athena/latest/APIReference/API_StartQueryExecution.html

[codecov]

Codecov Report

Merging #72 into master will decrease coverage by 0.07%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master      #72      +/-   ##
==========================================
- Coverage   92.22%   92.15%   -0.08%     
==========================================
  Files          13       13              
  Lines         939      943       +4     
==========================================
+ Hits          866      869       +3     
- Misses         73       74       +1

Impacted Files	Coverage Δ
pyathena/result_set.py	93.53% <ø> (ø)	⬆️
pyathena/pandas_cursor.py	100% <100%> (ø)	⬆️
pyathena/async_cursor.py	93.47% <100%> (ø)	⬆️
pyathena/connection.py	86.95% <100%> (+0.19%)	⬆️
pyathena/cursor.py	100% <100%> (ø)	⬆️
pyathena/common.py	88.57% <87.5%> (-0.65%)	⬇️

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