[BREAKING] Use github.com/k1LoW/expand to expand environment variables

[k1LoW]

Use https://github.com/k1LoW/expand

[codecov]

Codecov Report

Merging #324 (6935825) into main (5654076) will decrease coverage by 0.11%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #324      +/-   ##
==========================================
- Coverage   67.00%   66.89%   -0.12%     
==========================================
  Files          26       26              
  Lines        4334     4313      -21     
==========================================
- Hits         2904     2885      -19     
- Misses       1137     1140       +3     
+ Partials      293      288       -5     

Impacted Files	Coverage Δ
config/config.go	48.78% <100.00%> (-1.48%)	⬇️
datasource/datasource.go	40.14% <0.00%> (-2.12%)	⬇️

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