chore(deps): update main Nest dependencies

Motivation for this update: @nestjs/graphql 7.8.0 adds getApolloServer,
which is needed for things like apollo-server-testing's
createTestClient.

* nestjs/graphql#1101
* nestjs/graphql#1104
* https://github.com/nestjs/graphql/releases/tag/7.8.0

Note:

This directly updates the same packages that "yarn nest update" updates,
though "nest update" doesn't work with Yarn 2 yet.

Invocation (for reference):

yarn up @nestjs/common @nestjs/config @nestjs/core @nestjs/graphql
@nestjs/mongoose @nestjs/passport @nestjs/platform-express
@nestjs/terminus

yarn dedupe

package.json

@@ -21,14 +21,14 @@
     "test:e2e": "jest --config ./test/jest-e2e.json"
   },
   "dependencies": {
-    "@nestjs/common": "^7.4.4",
-    "@nestjs/config": "^0.5.0",
-    "@nestjs/core": "^7.4.4",
-    "@nestjs/graphql": "^7.7.0",
-    "@nestjs/mongoose": "^7.0.2",
-    "@nestjs/passport": "^7.1.0",
-    "@nestjs/platform-express": "^7.4.4",
-    "@nestjs/terminus": "^7.0.1",
+    "@nestjs/common": "^7.6.11",
+    "@nestjs/config": "^0.6.3",
+    "@nestjs/core": "^7.6.11",
+    "@nestjs/graphql": "^7.9.8",
+    "@nestjs/mongoose": "^7.2.3",
+    "@nestjs/passport": "^7.1.5",
+    "@nestjs/platform-express": "^7.6.11",
+    "@nestjs/terminus": "^7.1.0",
     "apollo-server-core": "2.16.1",
     "apollo-server-express": "2.16.1",
     "aws-sdk": "^2.770.0",