Update dependencies (#5518)

vendor/github.com/MakeNowJust/heredoc/heredoc.go

@@ -1,24 +1,31 @@
-// Copyright (c) 2014-2017 TSUYUSATO Kitsune
+// Copyright (c) 2014-2019 TSUYUSATO Kitsune
 // This software is released under the MIT License.
 // http://opensource.org/licenses/mit-license.php
 
 // Package heredoc provides creation of here-documents from raw strings.
 //
 // Golang supports raw-string syntax.
+//
 //     doc := `
 //     	Foo
 //     	Bar
 //     `
+//
 // But raw-string cannot recognize indentation. Thus such content is an indented string, equivalent to
+//
 //     "\n\tFoo\n\tBar\n"
+//
 // I dont't want this!
 //
 // However this problem is solved by package heredoc.
+//
 //     doc := heredoc.Doc(`
 //     	Foo
 //     	Bar
 //     `)
+//
 // Is equivalent to
+//
 //     "Foo\nBar\n"
 package heredoc