Pin to an exact pelias-parser version (2.1.0)

Historically we've kept most Pelias NPM dependencies on carat versions,
but because the Pelias Parser can cause changes in acceptance-test
results for any change (minor or even bug fix), we've kept it pinned to
a specific version so we can explicitly upgrade.

Recently, we were on a [hotfix
branch](#1531) of the parser, but
while switching back to using a version specification, we switched to
[using a carat
range](#1565).

While manually bumping the version on a frequent basis is a bit
annoying, it helps avoid any chance that unexpected or untested parser
changes will find their way into the API releases, so this change brings
us back to a pin of the current latest version of the Pelias Parser.

package.json

@@ -54,7 +54,7 @@
     "pelias-logger": "^1.2.0",
     "pelias-microservice-wrapper": "^1.10.0",
     "pelias-model": "^9.0.0",
-    "pelias-parser": "^2.0.0",
+    "pelias-parser": "2.1.0",
     "pelias-query": "^11.0.0",
     "pelias-sorting": "^1.2.0",
     "predicates": "^2.0.0",