MySQLColumn support `smallInteger` type

[gam6itko]

Realization for #127

[codecov[bot]]

Codecov Report

Merging #128 (1ce9082) into 2.x (ab6178f) will not change coverage. The diff coverage is n/a.

:exclamation: Current head 1ce9082 differs from pull request most recent head 43a48e1. Consider uploading reports for the commit 43a48e1 to get more accurate results

@@            Coverage Diff            @@
##                2.x     #128   +/-   ##
=========================================
  Coverage     94.68%   94.68%           
  Complexity     1666     1666           
=========================================
  Files            96       96           
  Lines          4494     4494           
=========================================
  Hits           4255     4255           
  Misses          239      239           

Impacted Files	Coverage Δ
src/Driver/MySQL/Schema/MySQLColumn.php	94.38% <ø> (ø)
src/Schema/AbstractColumn.php	98.59% <ø> (ø)

[roxblnfk]

Thank you