Go 1.16 -> Go 1.18

[mayitbeegh]

TL;DR

Starting from v1.46.0, golangci-lint no longer works with Go 1.16. This causes PR checks to fail, example https://github.com/flyteorg/flyteplugins/runs/6632158946?check_suite_focus=true
This PR fixes the PR checks by upgrading from Go 1.16 to Go 1.18.
End-to-end tested in flytepropeller and flyteadmin

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

How did you fix the bug, make the feature etc. Link to any design docs etc

Tracking Issue

Remove the 'fixes' keyword if there will be multiple PRs to fix the linked issue

Follow-up issue

NA

[codecov]

Codecov Report

Merging #266 (5a08e30) into master (82be16b) will decrease coverage by 0.00%.
The diff coverage is 60.00%.

❗ Current head 5a08e30 differs from pull request most recent head b46a28e. Consider uploading reports for the commit b46a28e to get more accurate results

@@            Coverage Diff             @@
##           master     #266      +/-   ##
==========================================
- Coverage   62.55%   62.55%   -0.01%     
==========================================
  Files         142      142              
  Lines        8961     8960       -1     
==========================================
- Hits         5606     5605       -1     
  Misses       2834     2834              
  Partials      521      521              

Flag	Coverage Δ
unittests	?

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Impacted Files	Coverage Δ
go/tasks/plugins/array/k8s/subtask_exec_context.go	81.72% <60.00%> (-0.20%)	⬇️

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