Update deps for Go and Dockerfile and switch to Go 1.17

[mszostok]

Description

Changes proposed in this pull request:

• Update deps for Go and Dockerfile
• Switch to Go 1.17

Done manually, as on dependabot bot has read-only token:

• https://github.com/dependabot/dependabot-core/issues/3253
• https://github.blog/changelog/2021-02-19-github-actions-workflows-triggered-by-dependabot-prs-will-run-with-read-only-permissions/