PHPStan のエラー修正

[nanasess]

Constant CALENDAR_ROOT already defined
https://github.com/EC-CUBE/ec-cube2/runs/5195065842?check_suite_focus=true#step:7:9

[codecov-commenter]

Codecov Report

Merging #522 (d210eaa) into master (bf7d535) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #522   +/-   ##
=======================================
  Coverage   54.40%   54.40%           
=======================================
  Files          76       76           
  Lines        9039     9039           
=======================================
  Hits         4918     4918           
  Misses       4121     4121           

Flag	Coverage Δ
tests	54.40% <ø> (ø)

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