Fix today highlight for nepali date

[MandipGiri]

• Fixed today highlight for nepali date.
• Fixes issues https://github.com/samit22/calendarN/issues/15

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Files	Coverage Δ
cmd/nepcal.go	93.81% <100.00%> (+0.13%)	:arrow_up:

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