build: add missing eslint dependency to loot-core

packages/loot-core/package.json

@@ -46,6 +46,7 @@
     "cross-env": "^7.0.3",
     "damerau-levenshtein": "^1.0.4",
     "date-fns": "2.0.0-alpha.27",
+    "eslint": "5.6.0",
     "esm": "^3.0.82",
     "fake-indexeddb": "^3.1.3",
     "fast-check": "^2.11.0",

yarn.lock

@@ -15302,6 +15302,7 @@ jest-snapshot@test:
     damerau-levenshtein: ^1.0.4
     date-fns: 2.0.0-alpha.27
     deep-equal: ^2.0.5
+    eslint: 5.6.0
     esm: ^3.0.82
     fake-indexeddb: ^3.1.3
     fast-check: ^2.11.0