fix: compatibility with mysql8.0

[jjeffcaii]

What this PR does:
fix compatibility with mysql8.0

Which issue(s) this PR fixes:

Fixes #449

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-commenter]

Codecov Report

Base: 35.96% // Head: 35.88% // Decreases project coverage by -0.07% ⚠️

Coverage data is based on head (0bf6e79) compared to base (186a3f8).
Patch coverage: 3.33% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #450      +/-   ##
==========================================
- Coverage   35.96%   35.88%   -0.08%     
==========================================
  Files         124      124              
  Lines       19966    20591     +625     
==========================================
+ Hits         7180     7389     +209     
- Misses      12000    12383     +383     
- Partials      786      819      +33     

Impacted Files	Coverage Δ
pkg/boot/discovery.go	53.57% <0.00%> (+10.57%)	⬆️
pkg/config/api.go	80.00% <ø> (ø)
pkg/config/config.go	0.00% <0.00%> (ø)
pkg/config/default.go	96.29% <ø> (+10.58%)	⬆️
pkg/config/diff.go	9.64% <ø> (-0.68%)	⬇️
pkg/config/equals.go	7.69% <ø> (+1.59%)	⬆️
pkg/config/etcd/etcd.go	78.81% <ø> (+5.12%)	⬆️
pkg/config/file/file.go	73.93% <ø> (-0.06%)	⬇️
pkg/config/nacos/nacos.go	41.17% <ø> (+2.56%)	⬆️
pkg/executor/redirect.go	4.54% <ø> (-0.37%)	⬇️
... and 19 more

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