remove unnecessary dependencies (#69)

Author: yuxiang-zhang

go.mod

@@ -2,8 +2,4 @@ module github.com/sourcegraph/go-diff
 
 go 1.14
 
-require (
-	github.com/google/go-cmp v0.5.2
-	github.com/shurcooL/go v0.0.0-20180423040247-9e1955d9fb6e // indirect
-	github.com/shurcooL/go-goon v0.0.0-20170922171312-37c2f522c041
-)
+require github.com/google/go-cmp v0.5.2

go.sum

@@ -1,8 +1,4 @@
 github.com/google/go-cmp v0.5.2 h1:X2ev0eStA3AbceY54o37/0PQ/UWqKEiiO2dKL5OPaFM=
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/shurcooL/go v0.0.0-20180423040247-9e1955d9fb6e h1:MZM7FHLqUHYI0Y/mQAt3d2aYa0SiNms/hFqC9qJYolM=
-github.com/shurcooL/go v0.0.0-20180423040247-9e1955d9fb6e/go.mod h1:TDJrrUr11Vxrven61rcy3hJMUqaf/CLWYhHNPmT14Lk=
-github.com/shurcooL/go-goon v0.0.0-20170922171312-37c2f522c041 h1:llrF3Fs4018ePo4+G/HV/uQUqEI1HMDjCeOf2V6puPc=
-github.com/shurcooL/go-goon v0.0.0-20170922171312-37c2f522c041/go.mod h1:N5mDOmsrJOB+vfqUK+7DmDyjhSLIIBnXo9lvZJj3MWQ=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=