Update dependencies

[nan-guo]

What do these changes do?

• Update coverage from 4.5.1 to 5.1.
• Update flake8 from 3.5.0 to 3.7.9.
• Update ipdb from 0.11 to 0.13.2.
• Update ipython from 7.0.1 to 7.13.0.
• Update pytest from 3.9.1 to 5.4.1.
• Update pytest-cov from 2.6.0 to 2.8.1.
• Update pytest-cov from 2.6.0 to 2.8.1.
• Update pytest-sugar from 0.9.1 to 0.9.3.
• Update pymysql to latest version 0.9.3
• Update docker from 3.5.1 to 4.2.0.
• Update sphinx from 1.8.1 to 3.0.3.
• Update sqlalchemy from 1.2.12 to 1.3.16
• Update uvloop from 0.11.2 to 0.14.0

[codecov]

Codecov Report

Merging #485 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #485   +/-   ##
=======================================
  Coverage   87.33%   87.33%           
=======================================
  Files           9        9           
  Lines        1192     1192           
  Branches      174      174           
=======================================
  Hits         1041     1041           
  Misses        122      122           
  Partials       29       29           

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[nan-guo]

Anyone can review this PR ?

[terricain]

Rebase this, as im pretty sure i just merged some fixes to examples, otherwise it looks ok

[nan-guo]

Hi @terrycain,
thanks for your review, rebased.