indexer: delete dead file (#3226)

Deletes an unused file from the indexer. The debug
file is created by hardhat and will point to the build info
file and this isn't needed by the indexer.
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

.changeset/eight-socks-hope.md

+---
+'@eth-optimism/indexer': patch
+---
+
+Delete dead file

indexer/contracts/ERC20.sol/ERC20.dbg.json

-{
-  "_format": "hh-sol-dbg-1",
-  "buildInfo": "../../build-info/d8a0f286587dfbd9a9d1e4f1e98e7119.json"
-}