chore(deps): Update dependency go to 1.20 (terraform-google-modules#999)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

test/integration/go.mod

@@ -1,10 +1,11 @@
 module github.com/terraform-google-modules/terraform-example-foundation/test/integration
 
-go 1.18
+go 1.20
 
 require (
 	github.com/GoogleCloudPlatform/cloud-foundation-toolkit/infra/blueprint-test v0.5.0
 	github.com/gruntwork-io/terratest v0.41.12
+	github.com/mitchellh/go-testing-interface v1.14.2-0.20210217184823-a52172cd2f64
 	github.com/stretchr/testify v1.8.2
 	github.com/tidwall/gjson v1.14.4
 	golang.org/x/oauth2 v0.6.0
@@ -48,7 +49,6 @@ require (
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mattn/go-zglob v0.0.4 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
-	github.com/mitchellh/go-testing-interface v1.14.2-0.20210217184823-a52172cd2f64 // indirect
 	github.com/mitchellh/go-wordwrap v1.0.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/tidwall/match v1.1.1 // indirect