Update to go 1.18 (#64)

go.mod

@@ -1,6 +1,6 @@
 module github.com/cli/go-gh
 
-go 1.16
+go 1.18
 
 require (
 	github.com/MakeNowJust/heredoc v1.0.0
@@ -9,13 +9,21 @@ require (
 	github.com/cli/shurcooL-graphql v0.0.1
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/henvic/httpretty v0.0.6
-	github.com/kr/pretty v0.1.0 // indirect
 	github.com/mattn/go-runewidth v0.0.13
 	github.com/stretchr/testify v1.7.0
 	github.com/thlib/go-timezone-local v0.0.0-20210907160436-ef149e42d28e
 	golang.org/x/sys v0.0.0-20210831042530-f4d43177bf5e
 	golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1
-	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
 	gopkg.in/h2non/gock.v1 v1.1.2
 	gopkg.in/yaml.v3 v3.0.1
 )
+
+require (
+	github.com/davecgh/go-spew v1.1.0 // indirect
+	github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542 // indirect
+	github.com/kr/pretty v0.1.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rivo/uniseg v0.2.0 // indirect
+	golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2 // indirect
+	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+)