all: Format code with gofumpt

See https://github.com/mvdan/gofumpt

tpl/internal/go_templates/texttemplate/example_test.go

@@ -34,7 +34,7 @@ Josie
 		Name, Gift string
 		Attended   bool
 	}
-	var recipients = []Recipient{
+	recipients := []Recipient{
 		{"Aunt Mildred", "bone china tea set", true},
 		{"Uncle John", "moleskin pants", false},
 		{"Cousin Rodney", "", false},