chore: Prepare 0.6.2 (#860)

- Contains the revert to [rust 2018](https://github.com/hyperium/tonic/pull/847).
- Bumps both tonic and tonic-build.
- tonic-build goes from 0.6.0 to 0.6.2 since there was no 0.6.1. I
  believe we want tonic and tonic-build versions to follow each other.

tonic/Cargo.toml

@@ -13,14 +13,14 @@ categories = ["web-programming", "network-programming", "asynchronous"]
 description = """
 A gRPC over HTTP/2 implementation focused on high performance, interoperability, and flexibility.
 """
-documentation = "https://docs.rs/tonic/0.6.1/tonic/"
+documentation = "https://docs.rs/tonic/0.6.2/tonic/"
 edition = "2018"
 homepage = "https://github.com/hyperium/tonic"
 keywords = ["rpc", "grpc", "async", "futures", "protobuf"]
 license = "MIT"
 readme = "../README.md"
 repository = "https://github.com/hyperium/tonic"
-version = "0.6.1"
+version = "0.6.2"
 
 [features]
 codegen = ["async-trait"]

tonic/src/lib.rs

@@ -79,7 +79,7 @@
 #![doc(
     html_logo_url = "https://raw.githubusercontent.com/tokio-rs/website/master/public/img/icons/tonic.svg"
 )]
-#![doc(html_root_url = "https://docs.rs/tonic/0.6.1")]
+#![doc(html_root_url = "https://docs.rs/tonic/0.6.2")]
 #![doc(issue_tracker_base_url = "https://github.com/hyperium/tonic/issues/")]
 #![doc(test(no_crate_inject, attr(deny(rust_2018_idioms))))]
 #![cfg_attr(docsrs, feature(doc_cfg))]