Unified go version api and api Dockerfile

[yutachaos]

Description

Proposed Changes

The go.mod specification of api is 1.14, but since the Dockerfile specification of api was 1.15, it was unified for consistency.

• api go.mod
  • https://github.com/globocom/huskyCI/blob/master/api/go.mod#L3
• api Dockerfile
  • https://github.com/globocom/huskyCI/blob/master/deployments/dockerfiles/api.Dockerfile#L1

[yutachaos]

Please added hacktoberfest-accepted label.