chore(deps): update dependency @grpc/grpc-js to ^0.7.8 (#400)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [@grpc/grpc-js](https://grpc.io/) ([source](https://togithub.com/grpc/grpc-node)) | devDependencies | patch | [`^0.7.7` -> `^0.7.8`](https://renovatebot.com/diffs/npm/@grpc%2fgrpc-js/0.7.7/0.7.8) |
| [@grpc/grpc-js](https://grpc.io/) ([source](https://togithub.com/grpc/grpc-node)) | dependencies | patch | [`^0.7.7` -> `^0.7.8`](https://renovatebot.com/diffs/npm/@grpc%2fgrpc-js/0.7.7/0.7.8) |

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test-fixtures/test-application-js/package.json

@@ -8,7 +8,7 @@
     "prettier-check": "prettier --check ./*.js"
   },
   "dependencies": {
-    "@grpc/grpc-js": "^0.7.7",
+    "@grpc/grpc-js": "^0.7.8",
     "grpc": "^1.24.2",
     "is-docker": "^2.0.0",
     "karma": "^4.4.1",

test-fixtures/test-application-ts/package.json

@@ -24,7 +24,7 @@
     "karma-mocha": "^1.3.0",
     "karma-chrome-launcher": "^3.1.0",
     "showcase": "file:./showcase-0.1.0.tgz",
-    "@grpc/grpc-js": "^0.7.7",
+    "@grpc/grpc-js": "^0.7.8",
     "grpc": "^1.24.2",
     "is-docker": "^2.0.0",
     "karma-webpack": "^4.0.2",