chore(deps): update dependency @grpc/proto-loader to ^0.7.0 (GoogleCloudPlatform#152)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [@grpc/proto-loader](https://grpc.io/) ([source](https://togithub.com/grpc/grpc-node)) | [`^0.6.2` -> `^0.7.0`](https://renovatebot.com/diffs/npm/@grpc%2fproto-loader/0.6.13/0.7.2) | [![age](https://badges.renovateapi.com/packages/npm/@grpc%2fproto-loader/0.7.2/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/npm/@grpc%2fproto-loader/0.7.2/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/npm/@grpc%2fproto-loader/0.7.2/compatibility-slim/0.6.13)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/npm/@grpc%2fproto-loader/0.7.2/confidence-slim/0.6.13)](https://docs.renovatebot.com/merge-confidence/) |

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package.json

@@ -35,7 +35,7 @@
     "@grpc/grpc-js": "~1.7.0"
   },
   "devDependencies": {
-    "@grpc/proto-loader": "^0.6.2",
+    "@grpc/proto-loader": "^0.7.0",
     "@google-cloud/spanner": "^6.0.0",
     "c8": "^7.7.2",
     "google-auth-library": "^8.0.0",