feat(api): update tonic to v0.10 and increase MSRV to 1.64 (#464)

BREAKING CHANGE:
This is a breaking change for users of `console-api` and
`console-subscriber`, as it changes the public `tonic` dependency to a
semver-incompatible version. This breaks compatibility with `tonic`
0.9.x and `prost` 0.11.x.

.github/workflows/ci.yaml

@@ -51,8 +51,8 @@ jobs:
         os: [ubuntu-latest, macos-latest, windows-latest]
         rust: [stable]
         include:
-          # Make 1.60 MSRV, as it's Tonic 0.9's MSRV.
-          - rust: 1.60.0
+          # Make 1.64 MSRV, as it's Tonic 0.10's MSRV.
+          - rust: 1.64.0
             os: ubuntu-latest
           # Try to build on the latest nightly. This job is allowed to fail, but
           # it's useful to help catch bugs in upcoming Rust versions.