Update Go version in source installation to work with latest Gitlab

What does this MR do?

When I tried source installation, go was old and failed to compile latest GitLab source caused by lack of new function around string replacement.

https://docs.gitlab.com/ee/install/installation.html

But, sorry, I forgot to take some screenshots, and my environment has already go 1.13.5, maybe getting reproducable command takes a time.

Screenshots

Sorry I did not take it.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team