fix: use original goleveldb package

[zivkovicmilos]

Description

This PR returns the original import declaration for https://github.com/syndtr/goleveldb.
After internal discussions, we've come to the conclusion that our fork repo is no longer required (since leveldb is no longer a dependency of the gno command)

cc @ilgooz @ajnavarro

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 44.84%. Comparing base (6760265) to head (2735824).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1870      +/-   ##
==========================================
- Coverage   47.54%   44.84%   -2.70%     
==========================================
  Files         388      459      +71     
  Lines       61242    67588    +6346     
==========================================
+ Hits        29117    30310    +1193     
- Misses      29686    34738    +5052     
- Partials     2439     2540     +101     

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