Update gosdk.yml: fix checkout to base branch

[boddumanohar]

Changes

Fixes

Tests

Tasks to complete before merging PR:

• [ ] Ensure system tests are passing. If not Run them manually to check for any regressions :clipboard:
• [ ] Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• [ ] Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• 0chain:
• gosdk:
• system_test:
• zboxcli:
• zwalletcli:
• Other: ...

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (90f8be4) 25.48% compared to head (9c47a04) 25.48%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## staging #1339 +/- ## ======================================== Coverage 25.48% 25.48% ======================================== Files 83 83 Lines 9365 9365 ======================================== Hits 2387 2387 Misses 6682 6682 Partials 296 296 ``` | [Flag](https://app.codecov.io/gh/0chain/blobber/pull/1339/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=0chain) | Coverage Δ | | |---|---|---| | [Unit-Tests](https://app.codecov.io/gh/0chain/blobber/pull/1339/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=0chain) | `25.48% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=0chain#carryforward-flags-in-the-pull-request-comment) to find out more.

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