Updates to go.mod

Changelog for 0.13.4:

• PR #423 Bump golang.org/x/crypto from 0.13.0 to 0.17.0 by @dependabot[bot]

Commits
9ba4228 Bump golang.org/x/crypto from 0.13.0 to 0.17.0 by @dependabot[bot]
2bf2c9d Update README.md by @alexellis

Changes: 0.13.3...0.13.4

Generated by Derek