enable credo duplicated code check

[ayrat555]

Credo was returning a false-negative duplicated code check result before these changes (#2432). The false-negative issue was fixed in 1.1 (https://github.com/rrrene/credo/blame/master/CHANGELOG.md#L18)

Currently, the number of characters of every duplicated code warning is lower than 80. I think it's containable.

resolves #2436

Changelog

• enable credo duplicated code check

[coveralls]

Pull Request Test Coverage Report for Build 12e10d45-3cab-49be-b5d1-1a73a5438d21

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 16 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.003%) to 79.268%

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Files with Coverage Reduction	New Missed Lines	%
apps/indexer/lib/indexer/block/catchup/fetcher.ex	16	69.23%

Totals
Change from base Build c49d5f25-83c9-4412-b651-f9aecb6f0de9:	0.003%
Covered Lines:	5154
Relevant Lines:	6502

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💛 - Coveralls

[vbaranov]

mass_threshold: 80

why 80 characters are chosen for the threshold? if to remove mass_threshold: 80, will be credo warnings? if yes, at which lines?

[ayrat555]

@vbaranov duplication is mostly in fetchers in GenServer callbacks. I think that containable. They're already abstracted with Indexer.Fetcher macro modulr
All warnings are described in #2436