Dependency updates. (#14033)

* Update dependencies.

* Fix tests.

vendor/github.com/jaytaylor/html2text/.travis.yml

@@ -1,13 +1,12 @@
 language: go
 go:
+  # n.b. For golang release history, see https://golang.org/doc/devel/release.html
   - tip
-  - 1.8
-  - 1.7
-  - 1.6
-  - 1.5
-  - 1.4
-  - 1.3
-  - 1.2
+  - "1.13.8"
+  - "1.12.17"
+  - "1.11.13"
+  - "1.10.8"
+  - "1.9.7"
 notifications:
   email:
     on_success: change