fix: Missing lru-cache dependency (#4600)

Relates to #4453.

Co-authored-by: Jesse Rosenberger <git@jro.cc>

CHANGELOG.md

@@ -13,6 +13,7 @@ The version headers in this history reflect the versions of Apollo Server itself
 
 ## v2.19.0
 
+- `apollo-server-core`: Explicitly include `lru-cache` dependency in `apollo-server-core`'s dependencies. [PR #4600](https://github.com/apollographql/apollo-server/pull/4600)
 - `apollo-server-core`: Update dependency for `@apollographql/graphql-playground-react` to `v1.7.34` to incorporate [`33c48183`](https://github.com/apollographql/graphql-playground/commit/33c48183229e59f0d21f7f4fdd57bed5a973a5cf) which, as an upstream change, should improve support for `graphql@15` features, like interfaces implementing interfaces.
 - `apollo-server-express`: Export the `GetMiddlewareOptions` type. [PR #4599](https://github.com/apollograpqh/apollo-server/pull/4599)
 

packages/apollo-server-core/package.json

@@ -46,6 +46,7 @@
     "graphql-tools": "^4.0.0",
     "graphql-upload": "^8.0.2",
     "loglevel": "^1.6.7",
+    "lru-cache": "^5.0.0",
     "sha.js": "^2.4.11",
     "subscriptions-transport-ws": "^0.9.11",
     "uuid": "^8.0.0",