fix: remove split2 from `devDependencies`

[Joxit]

The package split2 is present in both dependencies and devDependencies.

This causes an MODULE_NOT_FOUND error when we install the project with npm install --omit=dev

node:internal/modules/cjs/loader:998
  throw err;
  ^

Error: Cannot find module 'split2'
Require stack:
- /opt/pelias/lib/streams/recordStream.js
- /opt/pelias/lib/importPipeline.js
- /opt/pelias/import.js
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:995:15)
    at Function.Module._load (node:internal/modules/cjs/loader:841:27)
    at Module.require (node:internal/modules/cjs/loader:1067:19)
    at require (node:internal/modules/cjs/helpers:103:18)
    at Object.<anonymous> (/opt/pelias/lib/streams/recordStream.js:7:15)
    at Module._compile (node:internal/modules/cjs/loader:1165:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1219:10)
    at Module.load (node:internal/modules/cjs/loader:1043:32)
    at Function.Module._load (node:internal/modules/cjs/loader:878:12)
    at Module.require (node:internal/modules/cjs/loader:1067:19) {
  code: 'MODULE_NOT_FOUND',
  requireStack: [
    '/opt/pelias/lib/streams/recordStream.js',
    '/opt/pelias/lib/importPipeline.js',
    '/opt/pelias/import.js'
  ]
}

Node version: 16