Fix Token transfers CSV export

[vbaranov]

Motivation

Export of token transfers to CSV is broken at Tokens tab of address page

Changelog

Replace address with the checksummed address in /token-transfers-csv request

Checklist for your Pull Request (PR)

• I added an entry to CHANGELOG.md with this PR
• If I added new functionality, I added tests covering it.
• If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.
• I checked whether I should update the docs and did so by submitting a PR to https://github.com/blockscout/docs
• If I added/changed/removed ENV var, I submitted a PR to https://github.com/blockscout/docs to update the list of env vars at https://github.com/blockscout/docs/blob/master/for-developers/information-and-settings/env-variables.md and I updated the version to master in the Version column. Changes will be reflected in this table: https://docs.blockscout.com/for-developers/information-and-settings/env-variables.
• If I add new indices into DB, I checked, that they are not redundant with PGHero or other tools

[coveralls]

Pull Request Test Coverage Report for Build 402a2e52888370ccc12474e78fd9f0c8a54ab482-PR-3399

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.7%) to 67.677%

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Totals
Change from base Build 84625a710a08a367583493b4cc2df1a2da2eaad9:	0.7%
Covered Lines:	2054
Relevant Lines:	3035

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💛 - Coveralls