Revert "go mod support."

[zwfang]

Reverts #81

[codecov]

Codecov Report

Merging #82 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #82   +/-   ##
=======================================
  Coverage   99.38%   99.38%           
=======================================
  Files         119      119           
  Lines        2085     2085           
=======================================
  Hits         2072     2072           
  Misses          9        9           
  Partials        4        4

Impacted Files	Coverage Δ
src/0198_house_robber/house_robber.go	100% <ø> (ø)	⬆️
src/0376_wiggle_subsequence/wiggle_subsequence.go	100% <ø> (ø)	⬆️
src/0300_longest_increasing_subsequence/lis.go	100% <ø> (ø)	⬆️
src/0435_non_overlapping_intervals/dp_solution.go	87.5% <ø> (ø)	⬆️
...ainer_with_most_water/container_with_most_water.go	100% <ø> (ø)	⬆️
src/0004_median_of_two_sorted_arrays/motsa.go	100% <ø> (ø)	⬆️
...rsection_of_2_arrays/intersection_of_two_arrays.go	100% <ø> (ø)	⬆️
...nimum_window_substring/minimum_window_substring.go	100% <ø> (ø)	⬆️
..._others/largest_number_at_least_twice_of_others.go	100% <ø> (ø)	⬆️
src/0343_integer_break/integer_break.go	100% <ø> (ø)	⬆️
... and 2 more