Bump go-git to v5.6.1 (#123)

Author: zackproser

go.mod

@@ -3,11 +3,9 @@ module github.com/gruntwork-io/git-xargs
 go 1.14
 
 require (
-	github.com/go-git/go-git/v5 v5.3.0
+	github.com/go-git/go-git/v5 v5.6.1
 	github.com/golang/protobuf v1.4.3 // indirect
-	github.com/google/go-github v17.0.0+incompatible // indirect
 	github.com/google/go-github/v43 v43.0.0
-	github.com/google/go-github/v48 v48.0.0 // indirect
 	github.com/gruntwork-io/go-commons v0.8.2
 	github.com/pterm/pterm v0.12.42
 	github.com/sirupsen/logrus v1.7.0