Removes a deprecation notice when using ES modules.
(node:5615) [DEP0151] DeprecationWarning: No "main" or "exports" field defined in the package.json for /[redacted]/node_modules/gifsicle/ resolving the main entry point "index.js", imported from [redacted].
Default "index" lookups for the main are deprecated for ES modules.
Removes a deprecation notice when using ES modules.