update google-cloud-sdk to google-cloud-cli

I couldn't find a clear statement on this, but it seems like google has
deprecated the `google-cloud-sdk` package. We started seeing the following
error when running `docker build`:

```
The following packages have unmet dependencies:
 google-cloud-cli : Breaks: google-cloud-sdk but 463.0.0-0 is to be installed
E: Unable to correct problems, you have held broken packages.
```

I couldn't find any notice of deprecation, but I did find a few threads where
random people on the internet say it's been re-named to google-cloud-cli, so
I'm just giving it a go.

.devcontainer/release.Dockerfile

@@ -28,7 +28,7 @@ RUN apt update -y \
      jq \
      nodejs \
      docker-ce-cli \
-     google-cloud-sdk \
+     google-cloud-cli \
      && rm -rf /var/lib/apt/lists/*
 
 # Create a non-privileged "flow" user.