Set Go version of base image to 1.17

[tenzen-y]

What this PR does / why we need it:
Currently, Go version is unmatched between gomod and base image of Dockerfile for training operator. So, this PR upgrade Go version of base image.

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):
Fixes #

Checklist:

• Docs included if any changes are user facing

[coveralls]

Pull Request Test Coverage Report for Build 1488170146

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 24.099%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/controller.v1/mpi/mpijob_controller.go	2	75.31%

Totals
Change from base Build 1486793318:	-0.04%
Covered Lines:	1197
Relevant Lines:	4967

---

💛 - Coveralls

[gaocegege]

/lgtm
/approve

Thanks for your contribution! 🎉 👍

[terrytangyuan]

Thanks!

/lgtm

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gaocegege, tenzen-y, terrytangyuan

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [gaocegege,terrytangyuan]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[tenzen-y]

/retest