MAINT: Add environment.yaml at root path for user

[Zeroto521]

• closes #xxxx
• whatsnew entry

Set environment

• ./environment.yaml and ./environment-dev.yaml for developer
• ./ci/env/* for ci

[codecov]

Codecov Report

Merging #611 (9fd4080) into main (41f87b4) will decrease coverage by 0.20%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #611      +/-   ##
==========================================
- Coverage   99.59%   99.39%   -0.21%     
==========================================
  Files          85       85              
  Lines         997      997              
  Branches      103      103              
==========================================
- Hits          993      991       -2     
- Misses          1        2       +1     
- Partials        3        4       +1     

Impacted Files	Coverage Δ
dtoolkit/transformer/sklearn/OneHotEncoder.py	92.30% <0.00%> (-7.70%)	⬇️

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