feat(es8): support elasticsearch v8 (#275)

add support elasticsearch v8

BREAKING CHANGE: Pelias no longer supports elasticsearch v6

This change drops support for elasticsearch v6 in order to support v8.
The current recommended version remains v7.

package.json

@@ -37,10 +37,10 @@
     "@turf/length": "^6.0.2",
     "lodash": "^4.17.4",
     "minimist": "^1.2.0",
-    "pelias-config": "^4.12.0",
-    "pelias-dbclient": "^2.13.0",
+    "pelias-config": "^6.0.0",
+    "pelias-dbclient": "^3.0.0",
     "pelias-logger": "^1.2.1",
-    "pelias-model": "^9.2.0",
+    "pelias-model": "^10.0.0",
     "pelias-wof-admin-lookup": "^7.8.0",
     "split2": "^3.1.1",
     "through2": "^3.0.0"